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1
Meyer, Stephanie Kristen. "Effects of oestrogenic chemicals on the liver". Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3654.
Abstract (sommario):
Our environment and diet contains a variety of man-made endocrine disrupting chemicals which may pose a significant health threat for wildlife and humans. In particular, there is increasing concern regarding the adverse effects caused by xenoestrogens which are believed to trigger many endocrine-related diseases. Since high systemic levels of oestrogens are cholestatic, it was investigated whether xenoestrogens are able to cause adverse hepatic effects in vivo in mouse models and whether these effects are mediated by interaction with the murine oestrogen receptors (ERs). The food dye tartrazine has previously been shown to activate the human ERα and intraperitoneal injection caused cholestasis in mice. In this study, tartrazine failed to activate murine ERα and two murine ERβ variants in vitro suggesting that cholestasis occurred independent of the ERs. Data indicate, however, that tartrazine, its major metabolites and a contaminant inhibited murine dopamine sulfotransferase. Considering the role of sulfotransferases in bile acid secretion, these findings suggest that impairment of bile acid sulfation and subsequent secretion may be a key event in tartrazine-mediated cholestasis. Oral exposure to tartrazine caused inflammation in the liver and gastrointestinal tract in vivo in mice without evidence of cholestatic effects. Several soil extracts prepared from soil samples collected from around an urban landfill site activated human and murine ERα and two murine ERβ variants in vitro. Pooled oestrogenic soil extracts had mild cholestatic effects in a mouse model. Given the cholestatic features of the liver disease primary biliary cholangitis (PBC), which is linked to exposure to xenobiotics associated with a toxic environment and proximities to waste sites, environmental xenoestrogens could be a component of a xenobiotic insult that triggers PBC. These findings indicate that if significant exposure to environmental xenoestrogens occurs, they can have adverse hepatic effects and may be part of a trigger process in cholestatic liver diseases.
2
Oliveira, Rhaul. "Effects assessment of chemicals used in aquaculture". Doctoral thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/16297.
Abstract (sommario):
Doutoramento em BiologiaAquaculture provides food and income for millions of families worldwide being an activity with a high growth rate and with a strong potential for further expansion. Both producers and consumers are interested in a sustainable model of aquaculture development covering social, economic and environmental aspects. Such model implies to cope with the environmental impacts generated by aquacultures. The main objective of this work was to evaluate the use of chemicals applied in aquaculture farms and their harmful effects to aquatic organisms. Since more than 80% of global production of aquatic organisms is concentrated in Southwest Asia, special attention was given to the aquaculture in this region, particularly Thailand. Three different types of aquaculture scenarios were studied: shrimp farms and tilapia farms in cages and in earth ponds. Surveys and monitoring campaigns were conducted in several farms and the fate, use and application patterns of chemicals were identified. In cage farms the results indicated overuse/misuse of antibiotics, in shrimp farms the major group of chemicals used were disinfectants whereas in earth pond farms 1,7α-methyltestosterone (MT) was the most used. The results from the monitoring campaigns showed that the excessive use of chemicals was correlated to contamination of the surrounding environment namely with the antibiotics oxytetracycline (OTC) and enrofloxacin (ENR) in the cage farms, and with MT in the earth pond farms. In the laboratory, ecotoxicity assays were performed with antibiotics, disinfectants and pesticides using organisms belonging to different trophic levels. The disinfectants benzalkonium chloride (BKC), chlorhexidine gluconate (ChD) and glutaraldehyde (GA) were tested. BKC and ChD demonstrated to be very toxic to primary and secondary consumers. Moreover, an approach based on the species sensitivity distributions (SSD) was used to estimate the hazardous concentrations for 5 and 50 % of the species after BKC and GA exposure highlighting the sensitivity of primary producers to BKC exposure (HC5 = 10.8 μg/l). In the case of GA, different trophic levels showed similar sensitivities and a general HC5 = 300 μg/l was obtained. Additionally, a probabilistic environmental risk assessment was performed indicating a PAF (potentially affected fraction) of species > 5% for adverse effects of BKC in effluents and surface water. Concerning pesticides, both trichlorfon (TCF) and ivermectin (IVM) were studied. TCF showed to be extremely toxic to daphnids (48h- LC50 = 0.29 μg/l) and affected the acetilcolinesterase activity in D. magna and D rerio. IVM showed to be acutely toxic to D. rerio life stages (96h-LC50 = 18.5 μg/l for juveniles) and affected their development and biomarkers. In chronic exposures, IVM led to changes in the behaviour and growth of D. rerio juveniles (21d-LOEC < 0.25 μg/l). The antibiotics amoxicillin and OTC were not acutely toxic to aquatic organisms but both induced oxidative stress related enzymes of adults and embryos of D. rerio. Globally, most of the tested chemicals showed to compromise at least a particular group of organisms or sub-lethal parameters, requiring further long term studies so that the environmental risk assessment of these compounds can be refined. Lethal and sub lethal effects obtained to non-target organisms suggest a potential biodiversity loss in the aquatic ecosystems which might, thus, compromise the services provided by the ecosystems in a near future. Since the aquaculture relies directly on these services (e.g. high water quality) to succeed, there is an urgent need of control/education measures both in the use of chemicals in aquaculture and monitoring/mitigation of adverse impacts in natural ecosystems.
A aquacultura fornece sustento para milhões de famílias, sendo uma actividade em crescimento e com um forte potencial de expansão em todo o mundo. Há um interesse por parte de produtores e consumidores em desenvolver modelos sustentáveis de aquacultura abrangendo aspectos sociais, económicos e ambientais. Tais modelos implicam lidar com os impactos ambientais gerados pela aquacultura. O principal objectivo deste trabalho foi estudar o uso de produtos químicos usados nas aquaculturas e avaliar os seus efeitos nocivos para organismos aquáticos. Uma vez que mais de 80% da produção mundial de organismos aquáticos está concentrada no sudoeste da Ásia, foi dada especial atenção à aquacultura nessa região, particularmente na Tailândia. Três diferentes cenários foram considerados: aquaculturas de camarão, aquaculturas de tilápias cultivadas em gaiolas e em tanques escavados no solo. Em cada tipo foram realizados inquéritos e campanhas de monitoramento em várias aquaculturas nas quais foram averiguados o uso, destino e forma de aplicação de químicos. Os resultados indicaram o uso excessivo/inapropriado de alguns compostos, nomeadamente de antibióticos (em aquaculturas em gaiolas), de desinfectantes (em aquaculturas de camarão) e de 1,7α-metiltestosterona (MT) (em aquacultura de tilápias em tanques escavados). Os resultados das campanhas de monitorização mostraram que o uso excessivo de produtos químicos resulta na contaminação do meio ambiente com antibióticos (oxitetraciclina (OTC) e enrofloxacina (ENR)) nas aquaculturas em gaiola, e com MT nas aquaculturas de tilápias em tanques escavados. No laboratório, foram realizados ensaios de ecotoxicidade com antibióticos, desinfectantes e pesticidas usando organismos modelo pertencentes a diferentes níveis tróficos. Foram testados os desinfectantes, cloreto de benzalcónio (BKC), gluconato de clorexidina, e glutaraldeído (GA) sendo que os dois primeiros demonstraram ser muito tóxico para consumidores primários e secundários. Para uma análise integrada foi utilizada uma abordagem baseada nas distribuições de sensibilidade das espécies (DSE) com a qual se estimaram as concentrações perigosas (CP) para 5% e 50% das espécies após e exposição ao BKC e GA. O grupo dos produtores primários foi o grupo mais sensível à exposição ao BKC com CP5% = 10,8 μg/l enquanto para GA não foram encontradas diferenças de sensibilidade entre os grupos tróficos e, assim sendo, um valor geral de CP5% = 300 μg/l foi obtido. Além disso, uma análise probabilística dos riscos ambientais indicou uma fracção de espécies potencialmente afectada (FAPE) pelo BKC > 5% em efluentes e águas superficiais. Os pesticidas estudados foram o trichlorfon (TCF) e a ivermectina (IVM). O TCF foi extremamente tóxico para dafnídeos (48h-LC50 = 0,29 μg/l) e afectou também a actividade de acetilcolinesterase em D. magna e D. rerio. A IVM foi tóxica para adultos, juvenis e embriões de D. rerio (96h- CL50 = 18,5 μg/l para os juvenis) afectando o seu desenvolvimento e actividade de biomarcadores. Em exposições crónicas, IVM causou alterações no comportamento e crescimento em D. rerio juvenis (21d-LOEC <0,25 μg/l). Os antibióticos amoxicilina e OTC apresentam baixa toxidade para os organismos aquáticos, mas ambos induziram enzimas relacionadas estresse oxidativo em adultos e embriões de D. rerio. Em geral, a maioria dos químicos testados apresentaram toxicidade para algum grupo de organismo da cadeia trófica ou tiveram efeito a nível de parâmetros sub-letais, sendo portanto recomendados estudos de exposição crónica para que se possa refinar a avaliação de risco ambiental destes compostos. Os efeitos letais e sub-letais observados nos organismos não-alvo sugerem que pode haver uma perda da biodiversidade nos ecossistemas aquáticos, e assim, comprometer os serviços prestados pelos ecossistemas num futuro próximo. Sendo o sucesso da aquacultura dependente directo destes serviços (por exemplo, água de alta qualidade), há uma necessidade urgente de medidas de controlo/educação, tanto no uso de produtos químicos na aquacultura e monitoramento/mitigação dos impactos negativos destes nos ecossistemas naturais.
3
Goats, Geoffrey Charles. "Assessment of the effects of toxic chemicals upon earthworms". Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37706.
4
Merritt, Rebecca L. "The effects of environmental chemicals on glioblastoma cell growth". Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3475.
Abstract (sommario):
Thesis (M.S.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains vii, 78 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 70-78).
5
Li, Jing Adela, e 李晶. "Temperature-dependent toxic effects of selected chemicals on marine organisms". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/211051.
Abstract (sommario):
Anthropogenically driven climate change not only results in rising of sea temperature but also leads to more frequent and longer-lasting cold and heat waves. Meanwhile, coastal marine ecosystems are constantly challenged by increasing threats of chemical pollution. Temperature and chemical stressors can jointly affect the livelihood of marine organisms, but their combined effects are still poorly understood. Therefore, this study aimed to investigate the effects of thermal stress and chemical exposure on the marine medaka Oryzias melastigma, copepod Tigriopus japonicus and rotifer Brachionus koreanus. The four selected chemical contaminants included copper sulphate pentahydrate (Cu), dichlorophenyltrichloroethane (DDT), triphenyltin chloride and copper pyrithione. It was hypothesized that marine organisms are more susceptible to chemical exposure at both cold and warm extremes.
In vivo acute ecotoxicity tests were conducted over a wide temperature range to ascertain the relationship between thermal stress and chemical toxicity. For O. melastigma larvae, the lowest toxicity occurred at an optimum temperature range; the chemical toxicity further increased with temperature increase or decrease from this optimum, and exacerbated at extremely low and high temperatures. For T. japonicus and B. koreanus, the chemical toxicity generally increased with increasing temperature. Such inter-species dissimilarities were possibly due to differences in the uptake route, detoxification mechanism, avoidance behaviour and physiological response between the fish and the copepod or rotifer.
Experiments were conducted to evaluate the temperature-dependent physiological and biochemical responses, and thermal tolerance of O. melastigma larvae. The growth in the fish larvae showed an inverse and negatively skewed V-shape relationship with temperature, with a significant reduction in performance at both low and high thermal extremes. A mismatch between demand and supply of oxygen and energy under extremely cold and warm conditions was probably the primary cause of growth inhibition and metabolic impairment, leading to a temporary adaptation by a shift to anaerobiosis and an induction of heat shock proteins (HSPs).
Temperatures at both cold and warm extremes increased toxicities of DDT and Cu to O. melastigma larvae, resulting in restricted growth and interrupted oxygen consumption rate. The fish larvae modulated their metabolic pathway and produced stress proteins (i.e., HSPs and metallothioneins) for adaptation to the combined stress. However, such responses were disrupted by combinations of thermal extremes, in particular high temperature, and high chemical concentration. Most importantly, both DDT and Cu exposure significantly reduced the thermal tolerance of the fish larvae.
The interacting effect of temperature and Cu was also investigated on T. japonicus. The results showed that their combined effect could significantly reduce the survival, lengthen the developmental time and change the sex ratio of the copepod. Transcriptions of several stress-related genes (i.e., glutathione reductase, glutathione S-transferases and HSPs) in the adult T. japonicus were significantly affected by the joint-effect of temperature and Cu exposure, implying that these genes played essential roles in protecting the cellular integrity against the stresses.
This study advanced the understanding on the temperature-dependent toxicity of chemical contaminants to marine organisms, and provided valuable information and empirical models for deriving water quality criteria of chemical contaminants at various temperatures.published_or_final_version
Biological Sciences
Doctoral
Doctor of Philosophy
6
Oliveira, Eva Lima de Castro. "Ecotoxicological bioassays to evaluate the effects of chemicals in soil". Master's thesis, Universidade de Aveiro, 2008. http://hdl.handle.net/10773/801.
Abstract (sommario):
Mestrado em Toxicologia e EcotoxicologiaA utilização de compostos químicos e os consequentes efeitos em distintos compartimentos ambientais tem despertado muito interesse nos últimos anos.O aparecimento de Produtos de Higiene Pessoal no ambiente tem sido considerado como uma questão a ser colocada no domínio ambiental. A sua presença no ambiente ocorre devido á excessiva utilização por parte dosconsumidores e à sua incompleta remoção das estações de tratamento de águas residuais. Nessas estações os efluentes tratados e lamas sãonovamente reintroduzidos no ambiente e na maioria dos casosafectam os organismos residentes nas comunidades locais. Um outro tipo de compostos que também têm recebido atenção especial é os Hidrocarbonetos Policíclicos Aromáticos (HPAs), que desde a sua primeira aparição no solo, despertaramgrande curiosidade. Estes compostos são derivados da combustão incompletade compostos contendo carbono e hidrogénio e do processo diagénese. Com estetrabalho pretendemos avaliar a toxicidade do Triclosan num conjuntode organismos-teste terrestres, lumbricideos (Eisenia andrei), colêmbolos (Folsomia candida), enquitraideos (Enchytraeus albidus), incluindo dois tipos de plantas superiores (Triticum aestivum e Brassica rapa). Os parâmetros avaliados foram a germinação e crescimento das plantas e a sobrevivência/reprodução dos restantes organismos. Também foi realizado um ensaio de bioacumulação para avaliar o comportamento cinético de um HPA, o fenantreno em E. albidus. Para a determinação da concentração de fenantreno nos organismos bem como nos extractos de solo dois métodos foram usados: um por fluorescência e outro por cromatografia gasosa com espectometria demassa acoplado. Os resultados obtidos para a bateria de testes mostram uma relação dose-resposta para todas as espécies estudadas, Eisenia andrei é a que demonstra ser mais sensível, com um valor de CE50de aproximadamente 4mg/kg; a sensibilidade para cada espécie por ordem decrescente é a seguinteE. andrei> B. rapa> E. albidus > F. candida > T. aestivum. Verificou-se que os enquitraideos podem acumular e ser afectados por uma variedade decompostos orgânicos e inorgânicos, tais como os HPAs (fenantreno). Os parâmetros cinéticos estimados para o fenantreno foram 4.4 g solo/g organismo dia-1 para a taxa de assimilação (a) e 0,305 dia-1 para a taxa de eliminação (ke), o factor de bioacumulação calculado é de 14.3 para E. albidus.Todos os ensaios foram realizados com um solo padronizado Lufa 2.2. No âmbito geral, os testes ecotoxicológicos realizados, revelam a importânciade incluir diversas espécies, abrangendo diferentes níveis tróficos, devido á distinta sensibilidade dos organismos e modos de acção dos diferentes químicos. ABSTRACT: The usage of chemicalcompounds and their effects in the different environmental compartments have received a special attention in recent years. The occurrence of Personal Care Products (PCPs) in the environment hasbeen recognised as one of emerging issues in environmental chemistry. The widespread presence of PCPs in the environment is due to their extensive usefor direct use by the consumer and incomplete removal in wastewater treatment plants (WWTPs). WWTPs produce aqueous effluents for dischargeback into the environment, and sewage sludge and in a number of cases mayaffect the living organisms. Although Polycyclic Aromatic Compounds (PAHs) have received special attention since they were found in soils for the first time.PAHs are a class of several hundreds individual compounds containing at leasttwo condensed rings. They are produced by the incomplete combustion ofcompounds containing C and H, and diagenesis. With this study we assessed the toxicity of Triclosan in several standardized test organisms and parameters:seed emergence and growth of two terrestrial plants (Triticum aestivum and Brassica rapa); survival and reproduction of earthworms (Eisenia andrei), collembolans (Folsomia candida) andenchytraeids (Enchytraeus albidus). The results for the test battery shows a dose-response relationship for the all organisms tested and Eisenia andreiwas the most sensitive specie, with an EC50value of approximately 4mg/kg; with species chronic sensitivity decreasing from E. andrei > B. rapa > E. albidus > F. candida > T. aestivum. The overall results from the selected ecotoxicologicaltests, showed the importance of including species from different trophic levels due to the different species sensitivities and chemicals mode of action.Moreover, also the use of chronic endpoints is recommended.In the case of the PAH phenantrene (PHE), a study was performed in E. albidus, assessing the effects at the survival and reproduction, plus the bioaccumulation, to analysethe toxicokinetic behaviour of this chemical. Enchytraeus can accumulate and may be affected by PHE. Estimated kinetic parameters were 4.4g soil/g worm day-1 for the assimilation rate (a) and 0,305 day-1 for the elimination rate constant (ke), bioaccumulation factor was 14.3. In a general trend, the ecotoxicological tests performedshow the importance, of study different trophic levels, including different species, due to the different sensibility of the organisms and different chemicals modes of action. 6
7
Ribeiro, Fabianne de Araújo. "Combined effects of chemicals and ultraviolet radiation on Daphnia magna". Master's thesis, Universidade de Aveiro, 2009. http://hdl.handle.net/10773/871.
Abstract (sommario):
Mestrado em Ecologia, Biodiversidade e Gestão de EcossistemasO ambiente natural está frequentemente exposto a vários tipos de estresses, que podem ser de carácter químico, físico ou biológico, originados da actividade humana e dos processos de alteração climática. Os pesticidas são geralmente usados em práticas agrícolas para controlar doenças em vegetais e o aparecimento de pragas, e podem ser levados do solo para os sistemas aquáticos adjacentes aos locais de aplicação, onde representam um factor de stress para os organismos não-alvo. Além das exposições a químicos, o ambiente está sofrendo as consequências dos processos de alterações climáticas. Uma destas consequências é o aumento da radiação ultravioleta que chega à superfície terrestre devido à diminuição da concentração de ozono na estratosfera. O presente trabalho teve como objectivo principal elucidar alguns padrões e comportamentos biológicos relativamente a mudanças no ambiente. Para isto, com o intuito de prever as interacções entre stressores naturais e químicos, a radiação ultravioleta (RUV) e o fungicida carbendazim foram escolhidos como fontes de stressores natural e químico, respectivamente, e foram aplicados em combinação, como um exemplo das possíveis condições adversas que podem ser encontradas no ambiente. Os efeitos isolados da radiação ultravioleta em Daphnia magna foram avaliados através da utilização de uma lâmpada artificial de RUV, à qual os organismos foram expostos por um período máximo de 5 horas. Os experimentos de combinação entre RUV e carbendazim foram conduzidos com exposição constante ao químico, e uma única dose de radiação ultravioleta. Os parâmetros analisados foram sobrevivência, actividade alimentar, reservas energéticas e produção de juvenis de Daphnia magna. Para prever os efeitos das combinações, um dos modelos utilizados na análise de misturas de químicos e combinação de químicos com stressores naturais foi o utilizado. O modelo da Acção independente (AI) assume que ambos os componentes da combinação têm diferentes modos de acção, e actuam de forma independente sobre o organismo. Os efeitos são avaliados de acordo com as probabilidades de não-resposta do organismo a ambos os componentes da combinação. Há ainda outras formas de interacção entre os componentes da combinação que podem produzir um efeito mais severo (sinergismo) ou menos severo (antagonismo); os efeitos podem ser também dependentes do nível da dose aplicada ou do rácio entre os dois componentes da combinação Os resultados da exposição de Daphnia magna à radiação ultravioleta somente demonstraram um decréscimo na sobrevivência, na actividade alimentar e na produção de juvenis, com valores de dose-efeito muito próximos para todos os parâmetros, o que pode ser explicado pela diferença da sensibilidade deste organismo à radiação, de acordo com a idade em que são expostos. Os resultados das combinações entre carbendazim e RUV para o parâmetro sobrevivência foram bem ajustados ao modelo da acção independente, e não demonstraram nenhum desvio. Para a reprodução e a actividade alimentar, houve um desvio dependente do rácio entre os componentes, que demonstrou maior toxicidade para o carbendazim quando a radiação ultravioleta era o item dominante na combinação. Este estudo mostra a importância da avaliação de combinações entre químicos e stressores naturais. Neste caso, espera-se que o aumento na radiação aumente a sensibilidade dos organismos, como a Daphnia magna quando expostos a stressores químicos, como o fungicida carbendazim.
The natural environment and wildlife are often exposed to several chemicals, physical and biological stressors originated from human activities and climate changes. Pesticides are often used to control plant disease and pest in agricultural practices, and can runoff from the soil to adjacent aquatic systems, where it represents a stress factor for non-target organisms. In addition to chemical exposures, the natural environment is suffering from climate change processes. One of the consequences of that is the increasing amount of ultraviolet radiation reaching the earth’s surface due to depletion on stratospheric ozone. The present work aimed to elucidate some biological behaviors and patterns regarding changes in the environment. For that, to predict interactions between natural stressors and toxicants to Daphnia magna, the ultraviolet radiation (UVR) and the pesticide carbendazim were chosen as the source of natural and chemical stressors, respectively and were employed in combination with each other as an example of possible stress conditions that can be found worldwide in the environment. Single effects of ultraviolet radiation on Daphnia magna were assessed using an artificial UV source, by exposing the organisms to UV and visible light simultaneously, to a maximum period of 5 hours. Combined experiments of carbendazim and ultraviolet radiation were conducted with a constant chemical exposure and a single UVR dose. The parameters analyzed were survival, feeding activity, energy budget and offspring production of Daphnia magna. To predict effects of combined exposures, one of the reference models used for analysis of mixture toxicity and combination of chemical and natural stressor was applied. The Independent Action (IA) model assumes that both components of the combination have different modes of action, and act independently from each other; the effects of the combinations are based on the probabilities of nonresponse of the organism to both stressors. There are some deviations from the independent action model which can cause a more severe effect (synergism), or a less severe effect (antagonism); they might be also dose-level dependent or dose-ratio dependent. Results from single exposure of Daphnia magna to ultraviolet radiation showed a decrease in survival, feeding activity and offspring production, with similar dose-effect values, due to differences in the sensibility of the organism to UVR according to their age. Combined exposures of carbendazim and UVR for survival endpoint fitted to the IA model, showing no deviation patterns, while the response of reproduction and feeding activity were dose-ratio dependent, indicating a higher toxicity of carbendazim when ultraviolet radiation was the dominant item in the combination. This study shows the importance of evaluate the combined effects of chemicals and natural stressors. In this case, UVR increase is expected to enhance the sensitivity of organisms as D. magna when exposed to chemical stressors like the fungicide carbendazim.
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Ferreira, Nuno Gonçalo de Carvalho. "The effects of chemicals in isopods: a multi-organizational evaluation". Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14095.
Abstract (sommario):
Doutoramento em BiologiaThe global aim of this thesis was to evaluate and assess the effects of a pesticide (dimethoate) and a metal (nickel), as model chemicals, within different organization levels, starting at the detoxification pathways (enzymatic biomarkers) and energy costs associated (energy content quantification, energy consumption and CEA) along with the physiological alterations at the individual and population level (mortality), leading to a metabolomic analysis (using liquid 1H-NMR) and finally a gene expression analysis (transcriptome and RT-qPCR analysis). To better understand potential variations in response to stressors, abiotic factors were also assessed in terrestrial isopods such as temperature, soil moisture and UV radiation. The evaluation performed using biochemical biomarkers and energy related parameters showed that increases in temperature might negatively affect the organisms by generating oxidative stress. It also showed that this species is acclimated to environments with low soil moisture, and that in high moisture scenarios there was a short gap between the optimal and adverse conditions that led to increased mortality. As for UV-R, doses nowadays present have shown to induce significant negative impact on these organisms. The long-term exposure to dimethoate showed that besides the neurotoxicity resulting from acetylcholinesterase inhibition, this stressor also caused oxidative stress. This effect was observed for both concentrations used (recommended field dose application and a below EC50 value) and that its combination with different temperatures (20ºC and 25ºC) showed different response patterns. It was also observed that dimethoate’s degradation rate in soils was higher in the presence of isopods. In a similar study performed with nickel, oxidative stress was also observed. But, in the case of this stressor exposure, organisms showed a strategy where the energetic costs necessary for detoxification (biomarkers) seemed to be compensated by positive alterations in the energy related parameters. In this work we presented for the first time a metabolomic profile of terrestrial isopods exposed to stressors (dimethoate and niquel), since until the moment only a previous study was performed on a metabolomic evaluation in nonexposed isopods. In the first part of the study we identify 24 new metabolites that had not been described previously. On the second part of the study a metabolomic profile variation of abstract non-exposed organism throughout the exposure was presented and finally the metabolomic profile of organisms exposed to dimethoate and nickel. The exposure to nickel suggested alteration in growth, moult, haemocyanin and glutathione synthesis, energy pathways and in osmoregulation. As for the exposure to dimethoate alterations in osmoregulation, energy pathways, moult and neurotransmission were also suggested. In this work it was also presented the first full body transcriptome of a terrestrial isopod from the species Porcellionides pruinosus, which will complement the scarce information available for this group of organisms. This transcriptome also served as base for a RNA-Seq and a RT-qPCR analysis. The results of the RNA-Seq analysis performed in organisms exposed to nickel showed that this stressor negatively impacted at the genetic and epigenetic levels, in the trafficking, storage and elimination of metals, generates oxidative stress, inducing neurotoxicity and also affecting reproduction. These results were confirmed through RT-qPCR. As for the impact of dimethoate on these organisms it was only accessed through RT-qPCR and showed oxidative stress, an impact in neurotransmission, in epigenetic markers, DNA repair and cell cycle impairment. This study allowed the design of an Adverse Outcome Pathway draft that can be used further on for legislative purposes.
Os efeitos negativos de contaminantes de origem antropogénica que aparecem no meio ambiente têm um impacto negativo muitas vezes em organismos considerados benéficos. Dentro deste grupo de organismos podemos incluir os isópodes terrestres, detritivorous, cuja função se baseia na fragmentação de matéria vegetal, que poderão posteriormente ser facilmente colonizados por bactérias e os seus nutrientes incorporados nos solos. Para avaliar os efeitos de contaminantes em isópodes terrestres, mais concretamente na espécie Porcellionides pruinosus, foram usados como modelos o metal níquel e o pesticida dimetoato, fazendo uma abordagem em diferentes níveis organizacionais. O trabalho iniciou-se pela avaliação do impacto a nível das vias de destoxificação (biomarcadores enzimáticos) e reservas energéticas (quantificação das reservas, consumo energético e alocação da energia celular), juntamente com alterações a nível dos indivíduos e da população (mortalidade), passando por uma análise de metabolómica (usando 1H-RMN de líquidos) e finalmente uma análise da expressão génica (transcriptoma e RT-qPCR). De forma a melhor entender as variações que podem ocorrer oriundas de variações de fatores abióticos, foi também realizado um estudo sob os efeitos da variação de temperatura, humidade do solo e radiação UV em isópodes terrestres. A avaliação feita a nível dos biomarcadores bioquímicos, quantificação das reservas e parâmetros energéticos demonstrou que o aumento da temperatura iria afectar negativamente os organismos devido ao stress oxidativo gerado. Tendo em conta que esta espécie está aclimatada a ambientes com solos com humidades baixas, a exposição a solos com humidades superiores mostrou a existência de um pequeno intervalo entre o que são consideradas condições óptimas e condições bastante adversas, sendo aí verifica uma elevada mortalidade. Os efeitos da radiação UV demonstraram que as doses que actualmente chegam à superfície do planeta constituem uma ameaça para os isópodes terrestres. A avaliação feita à toxicidade do dimetoato em biomarcadores bioquímicos, reservas e parâmetros energéticos, demonstrou que além da toxicidade já esperada (inibição da enzima acetilcolinesterase), este stressor induz igualmente stress oxidativo. Este efeito foi observado para ambas as concentrações usadas (dose recomendada de aplicação em campo e dose próxima do EC50) e que a sua combinação com diferentes temperaturas (20ºC resumo e 25ºC) dava origem a diferentes padrões de resposta. Também foi observado que a taxa de degradação do dimetoato era superior em solos com a presença de isópodes. Num estudo semelhante ao anterior, realizado com níquel, foi observada toxicidade induzida por stress oxidativo. No entanto os organismos expostos a este stressor apresentam uma estratégia em que os custos energéticos associados à destoxificação (biomarcadores bioquímicos) parecem ser compensados com alterações positivas a nível dos parâmetros energéticos. Neste trabalho é apresentado pela primeira vez o perfil metabolómico de isópodes terrestres expostos a dimetoato e níquel, sendo que até à data apenas um estudo tinha apresentado o perfil metabólico de isópodes em situação de homeostasia. Na primeira parte do estudo é apresentado o perfil metabólico que identifica 24 novos metabolitos que ainda não tinham sido descritos anteriormente. Numa segunda parte é apresentada uma variação do perfil de organismos não expostos ao longo do ensaio e finalmente são apresentadas as variações metabólicas em organismos expostos a dimetoato e a níquel. Os resultados mostraram que ambos os stressores causaram alterações que eram dependentes da concentração e do tempo. Quando expostos a níquel os organismos evidenciam alterações ao nível do crescimento, muda e síntese de hemocianina e glutationas, alterações ao nível das vias energéticas e na osmorregulação. Em relação aos efeitos da exposição a dimetoato, foram observadas alterações a nível da osmorregulação, das vias energéticas e na muda, mas também ao nível da neurotransmissão. Neste trabalho é apresentado pela primeira vez um transcriptoma completo de um isópode terrestre, da espécie Porcellionides pruinosus. Este transcriptoma veio complementar a atual, mas parca, informação disponível sobre este grupo de organismos. Tendo como base o transcriptoma, foi posteriormente realizada uma análise de RNA-Seq e de RT-qPCR. A análise de RNA-Seq foi realizada apenas em organismos expostos a níquel e mostrou que este stressor tem um impacto ao nível genético e epigenético, no transporte, acumulação e eliminação de metais, gera stress oxidativo, neurotoxicidade e afecta também a reprodução. Estes resultados foram confirmados pela análise feita através de RT-qPCR. Em relação aos efeitos de dimetoato nestes organismos a nível genómico, a sua avaliação foi apenas realizada através de RT-qPCR. Foi observado que este stressor gera stress oxidativo, neurotoxicidade, tem um impacto em marcadores epigenéticos, na reparação de ADN e provoca alterações a nível da divisão celular. Este estudo permitiu a realização de uma “Adverse Outcome Pathway” (AOP) que poderá ser usada mais tarde para fins legislativos.
9
Lough, Kerry Frances. "The Short and Long-term Effects of Herbicide Application in Maine Clearcuts on Ant Communities (Hymenoptera: Formicidae)". Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/LoughKF2003.pdf.
10
Czarnota, Jenna. "Modeling Spatially Varying Effects of Chemical Mixtures". VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4361.
Abstract (sommario):
Cancer incidence is associated with exposures to multiple environmental chemicals, and geographic variation in cancer rates suggests the importance of accommodating spatially varying effects in the analysis of environmental chemical mixtures and disease risk. Traditional regression methods are challenged by the complex correlation patterns inherent among co-occurring chemicals, and the applicability of geographically weighted regression models is limited in the setting of environmental chemical risk analysis. In comparison to traditional methods, weighted quantile sum (WQS) regression performs well in the identification of important environmental exposures, but is limited by the assumption that effects are fixed over space. We present an extension of the WQS method that models spatially varying chemical mixture effects called local weighted quantile sum (LWQS) regression, and assess through a simulation study its ability to identify important environmental risk factors over space. We use two different approaches to estimate the LWQS model based on variable subspaces. One uses an ensemble of variable subsets of the same size, and the other selects the best subset over a range of candidate subset sizes according to the model goodness-of-fit. We assess the performance of both estimation methods in simulated scenarios that incorporate increasingly complex levels of spatial dependency in the model, and consider correlation patterns from observed exposure data. The results demonstrate that LWQS has the ability to replicate spatially dependent mixture effects and can correctly identify important exposures in a mixture of environmental chemicals. In all scenarios, the best subset approach correctly chose an index containing only the important chemicals and improved on the accuracy of the chemical importance weights in comparison with the ensemble solutions. Future work will evaluate if the ensemble subset approach has better relative performance with larger chemical mixtures of highly correlated components.
11
Mills, Lesley Judith. "Effects of endocrine-disrupting chemicals on fish reproduction and reproductive indicators /". View online ; access limited to URI, 2006. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3248238.
12
Adams, N. "Algal toxicity in the prediction of environmental effects of organic chemicals". Thesis, University of Hertfordshire, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355316.
13
McDaniel, Charles Russell. "Effects of holding tank odor control chemicals on aerobic wastewater treatment". Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/44686.
Abstract (sommario):
Three odor control chemicals and formaldehyde were tested for detrimental affects on activated sludge using bench-scale bioreactors. Slug fed and continuous flow bioreactors were monitored for changes in suspended solids, specific oxygen uptake rate, sludge settling and compaction, and effluent COD. The biodegradability of dyes and the generation of foam was also measured.
Formaldehyde and the formaldehyde·based odor control
chemical 'Aqua-Kem" damaged the ability of activated
sludge to treat wastewater. They resulted in deceased
suspended solids concentrations and increased effluent
COD. Formaldehyde hinders the utilization of normal
wastewater substrate by activated sludge. The dye in
"Aqua-Kem" is not biodegradable, and surfactants in the
chemical generate foam.
Master of Science
14
Fallahi, Esmaeil, Michael Kilby e John W. Moon. "Effects of Various Chemicals on Dormancy, Maturity and Thinning of Peaches". College of Agriculture, University of Arizona (Tucson, AZ), 1990. http://hdl.handle.net/10150/215745.
Abstract (sommario):
Effects of 5 chemicals on the reduction of dormancy and early maturity of peaches were studied for 3 years under the desert climatic condition of Southwest Arizona. CuSO4, urea and particularly hydrogen cyanamide reduced the dormancy and enhanced blooming. Application of hydrogen cyanamide in October induced full bloom in November (1 month after application) and produced fruit. Late November was the most appropriate time for application of hydrogen cyanamide, and fruit were harvested 10 days before normal time in April. No difference was found between 5% and 3% (V/V) of hydrogen cyanamide in the time of blooming; however, rate at 5% always caused some phytotoxicity. Application of hydrogen cyanamide at 1% before bloom and at full bloom produced the same size of commercially packed fruit as hand-thinned ones.
15
Jung, Mun-Yhung. "Effects of carotenoids and tocopherols on the chlorophyll sensitized photooxidation of soybean oil". The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1382551295.
16
Helmestam, Malin. "Effects of Endocrine Disrupting Chemicals on Human Endometrial Endothelial Cells In Vitro". Doctoral thesis, Uppsala universitet, Obstetrik & gynekologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-196730.
Abstract (sommario):
Evidence from an abundant number of studies suggests that human female reproductive functions have become impaired over the past half century and that there might be a relationship between endocrine disrupting chemicals (EDCs) and reduced fertility. It is, however, not known by what mechanisms EDCs affect different reproductive functions such as endometrial receptivity, embryo implantation and placentation. The endometrium is continuously changing its morphological and functional properties, responding to cyclic changes of oestrogen and progesterone levels during the menstrual cycle. These changes include monthly preparation for embryo implantation through changed endometrial angiogenic activity and consequent changes in endometrial vasculature. Use of primary human endometrial endothelial cells (HEECs) in this work was evaluated as a possible screening tool for effects caused by EDCs on human endometrial vasculature and subsequently on various endometrial functions. In this study HEEC and endometrial stromal cells were isolated. HEECs were grown in monocultures, and together with stromal cells in co-cultures, and exposed to endocrine active substances. These were cadmium, which has oestrogenic properties, tamoxifen, with anti-oestrogenic effects, mifepristone, which is an anti-progestin, and bisphenol A, with oestrogenic properties. The effects were evaluated by using proliferation and viability assays, migration and tube formation assays, quantitative PCR (qPCR), immunohistochemistry and western blot. Cadmium affected the expression of angiogenesis-related genes, and caused different effects in HEECs cultured alone vs. HEECs co-cultured with stromal cells. Tamoxifen altered the expression of angiogenesis-related genes and reduced HEEC migration, thus having an anti-angiogenic effect. Mifepristone caused reduced formation of tubular structures in tube-formation assays involving HEECs co-cultured with stromal cells. Bisphenol A promoted tube formation in co-cultured HEECs which was related to changes in the expression of several angiogenesis-related genes as well as up-regulated expression of VEGF-D protein. In conclusion, we showed that EDCs have the ability to induce changes in endometrial angiogenic activity in vitro and may thus disturb normal endometrial functions related to fertility and pregnancy. HEECs grown in vitro may provide valuable information on the effects of EDCs on human endometrial functions. However, this model is not suitable as a large-scale screening tool.
17
Papoulias, Diana. "The effects of endocrine disrupting chemicals on the sexual development of fish /". free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3036850.
18
Moreman, John. "Tissue targets, molecular mechanisms and health effects of bisphenolic chemicals in zebrafish". Thesis, University of Exeter, 2016. http://hdl.handle.net/10871/27797.
Abstract (sommario):
Bisphenol A (BPA) is a chemical incorporated in plastics and resins used for food and beverage containers that has been shown to have estrogenic activity. The fact that BPA possess this activity should not be surprising as it was originally explored for use as a pharmaceutical estrogen. Exposure to BPA has been associated with adverse reproductive and developmental effects in wildlife and laboratory animal models. There are also associations between exposure in humans and adverse health effects, although some of these findings are controversial. The mechanism(s) of action of BPA are well researched, however there is no definitive explanation for the frequently reported discrepancies between in vitro and in vivo studies. Metabolic activation of BPA in vivo has been suggested as a possible reason for this discrepancy in estrogenic potency. As public awareness of the possible health effects of BPA increases manufacturers have increasingly started to use replacement chemicals as monomers in materials that can be labelled as BPA-free. However there is still little information on the estrogenic potency of these structurally similar bisphenol chemicals or how they may affect health outcomes, as observed with BPA. The studies conducted in this thesis therefore aimed to investigate the tissue targets, molecular mechanisms and health effects of BPA, its related chemicals Bisphenol S (BPS), Bisphenol F (BPF) and Bisphenol AF (BPAF) and the BPA metabolite 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP). For this work, a novel ERE transgenic (ERE-TG) zebrafish, that expresses green fluorescent protein (GFP) in response to activation of ERE was employed. These fish can be applied to identify body targets of environmental estrogens in real time with high sensitivity and specificity. BPA, BPF, BPS and BPAF were shown to all preferentially target the heart in ERE-TG zebrafish and GFP induction occurred first in the heart out of the different responding body tissues. The response to BPA was shown to be dependent on the classical estrogen receptor (ER) signalling pathway. However concentrations necessary to induce this response varied for the different bisphenols, with the rank order of potency of BPAF > BPA = BPF > BPS. Bioconcentration factors of the bisphenols were 4.5, 17.8, 5.3 and 0.067 for exposures to 1000 µg BPA/l, 1000 µg BPF/l, 100 µg BPAF/l and 50000 µg BPS/l respectively. These data indicate bioavailability is an important consideration in the differing estrogenic potencies of the different bisphenols. The toxicities of the different bisphenols on early life stage zebrafish followed a similar rank potency order as for the estrogenic activity (BPAF>BPA>BPF>BPS). Specific morphological abnormalities were observed for the different bisphenolic chemical treatments in the toxicity assessments, possibly suggesting that they may act through different ways in inducing their toxic effects. It is recognised that the toxicities for the bisphenolic chemicals were observed at concentrations several orders of magnitude higher than those measured in most aquatic environments and thus the threat they pose to wildlife health might be considered as relatively low, except in circumstances where short but high exposures may occur from accidental release into the environment. The BPA metabolite MBP was found to be up to 1000-fold more potent than the parent compound as an estrogen in ERE-TG fish. The heart was a key target tissue for MBP, as observed for the other bisphenolic compounds. The atrioventricular valves and bulbus arteriosus were identified as the primary targets within the heart. MBP was not measured in zebrafish embryos exposed to BPA and whether this is produced as a metabolite in zebrafish is still not known. Morpholino knockdown of specific ER subtypes indicated that esr1 is a major pathway for the estrogenic response to BPA in the heart during early life stages of zebrafish. Video capture and analysis was used to assess the cardiovascular health of zebrafish exposed to BPA and it was found that at very high exposure concentrations (2500 µg/l) BPA could induce an unstable atrial:ventricular beat ration in 5 dpf larvae and reduced heart beat rate in 14 dpf. In the final study of this thesis transcriptomic profiling was conducted on hearts extracted from 96 hpf ERE-TG zebrafish larvae exposed to BPA. The findings demonstrated that BPA, at an exposure concentration of 150 µg/l caused a down-regulation of a number of genes associated with ion transport and cell-to-cell communication, functions that are essential in maintaining a regular and consistent heart rate. These effect mechanisms may help to explain the effects on the heart seen at the higher BPA exposure concentrations in the previous chapter, although this would need more extensive work to draw any such associations with good confidence Overall, the findings presented in this thesis have provided a body of evidence to show that all of the bisphenolic chemicals tested possess estrogenic activity and as such have the potential for health effects in wildlife and also to humans. It is also the case however that currently in most ambient environments concentrations of these bisphenolic chemicals are far below those that could induce adverse health outcomes. The work in this thesis re-enforces the importance of understanding metabolic activation of chemicals in vivo. It furthermore illustrates the power of transgenic fish and an integrated approach for gaining greater insight into potential health effects of chemicals.
19
Metali, Faizah Haji. "Factors controlling Al accumulation in plants : effects of phylogeny, soil conditions and external nutrient supply". Thesis, University of Aberdeen, 2010. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=165794.
Abstract (sommario):
I used a data-set of 986 plant species (from 493 genera in 195 families) obtained from a literature search and a new data collection for 58 tropical tree species (from 31 genera in 18 families) growing in two contrasting forest types in Brunei Darussalam: mixed dipterocarp forest on moderately infertile ultisols and fluvisols, and heath forest on acidic and nutrient-poor spodosols. I provide statistical evidence for the existence of discreet groups of species representing Al accumulators and non-Al accumulator based on foliar Al concentrations. The threshold foliar Al concentration was higher for tropical plants (range 2.3-3.9 mg Al g-1) than temperate plant (1.1 mg Al g-1). Species’ mean log foliar Al concentration was also higher for tropical (0.73 ± 1.11 mg Al g-1) than temperate plants (0.16 ± 1.07 mg Al g-1). I used the tropical Al accumulating shrub Melastoma malabathricum L. as a study species to test the hypotheses that growth would be stimulated by Al addition. Growth of M. malabathricum seedlings was stimulated by Al addition when the external supply of macronutrients was very low, and this growth response was associated with an increase in net assimilation rate and specific leaf area. Foliar Al concentration was positively correlated with foliar concentrations of Ca and Mg across 16 Al accumulator species sampled in the field study in Brunei Darussalam, while foliar Al and K concentrations were correlated positively in M. malabathricum seedlings growing in the solution culture experiments. These positive correlations contradict the hypothesis that Al inhibits the uptake of nutrient cations and they may contribute to the positive growth response to Al addition in Al accumulator plants.
20
Lee, Peter John. "Statistical evaluation of tribological effects of some fluids on sliding aluminium alloys". Thesis, University of Hertfordshire, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245456.
21
Tinney, Brooke Merrill. "The effects of deinking on the coating compounds used on carbonless business forms /". Online version of thesis, 1991. http://hdl.handle.net/1850/11285.
22
Rodriguez, Indalesio. "Composition related effects on thermal reactivity of organic feedstocks /". Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/9895.
23
Carlsson, Gunnar. "Fish and amphibians as test organisms for evaluation of effects caused by chemicals /". Uppsala : Dept. of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/200761.pdf.
24
Jacob, Annie Philip. "Ecological effects of chemicals used in pond culture of catfish and percid fishes". Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1211989438.
25
Silva, Elisabete Alessandra Ferreira. "Oestrogenic chemicals in the environment : studies of mixture effects and mechanisms of action". Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407072.
26
Wollenberger, L. "Toxicity tests with crustaceans for detecting sublethal effects of potential endocrine disrupting chemicals". Kgs. Lyngby : Environment & Resources, Technical University of Denmark, 2005. http://www2.er.dtu.dk/publications/fulltext/2005/MR2005-012.pdf.
27
Deardorff, Angela Diane. "Effects of insecticide and adjuvant mixtures on cladocerans and Coho salmon". Online access for everyone, 2007. http://www.dissertations.wsu.edu/Thesis/Fall2007/a_deardorff_082107.pdf.
28
Jones, Maren Bell. "Effects and interactions of endocrine disrupting chemicals and diet on the mouse reproductive system". Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5006.
Abstract (sommario):
Thesis (M.A.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on October 29, 2007) Vita. Includes bibliographical references.
29
Yeung, Chiu Wai. "Neurotoxicological effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on cultured neurons". HKBU Institutional Repository, 2004. http://repository.hkbu.edu.hk/etd_ra/529.
30
Peiris, Dinithi. "Effects of known reproductive toxicants of sperm function and nuclear integrity in the hamster". Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287651.
31
Gulston, Melanie Katharine. "The effects of the sunscreen chemicals Padimate-O and 2-ethylhexyl-P-methoxycinnamate on DNA". Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301520.
32
Wei, Xi. "Environmental screening of endocrine-disrupting chemicals and biological characterization of their effects on reproductive health". HKBU Institutional Repository, 2011. http://repository.hkbu.edu.hk/etd_ra/1225.
33
Means, Nathan. "Effects of glyphosate and foliar amendments on soil microorganisms in soybean /". free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p3164527.
34
Sen, Sumitra. "Cellular and Molecular Effects of Mono-(2-ethylhexyl) phthalate (MEHP) in Testicular Cancer". Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36844.
Abstract (sommario):
Phthalates are endocrine-disrupting chemicals (EDCs) that are known testicular toxicants, used commonly as industrial plasticizers that are found in everyday items. Di-(2-ethylhexyl) phthalate (DEHP) is the most abundant phthalate in the environment, and its primary metabolite mono-(2-ethylhexyl) phthalate (MEHP) is ten-fold more potent. The purpose of this study is to examine the cellular and molecular effects of MEHP in the development of testicular cancer. Proliferation was measured for NT2 cells exposed to 10µM and 100µM MEHP at 24 and 48 hours and for cells under controlled conditions. Methylation-specific PCR (MSP) was used to determine the methylation status of the promoter region of key testicular genes post exposure to MEHP. MEHP caused a dose-dependent negative effect on proliferation and significantly altered methylation levels for key testicular genes following exposure to 10µM MEHP and 100µM, as compared to controls. This suggests that MEHP alters proliferation and methylation of testicular tumour cells in a time- and dose-dependent manner.
35
Chu, Yu-Hsuan. "Custom Fluorophores for Investigating the Cellular Uptake Mechanisms and Side-Effects of Pharmaceuticals". PDXScholar, 2015. http://pdxscholar.library.pdx.edu/open_access_etds/2343.
Abstract (sommario):
There is a significant current need to elucidate the molecular mechanisms of the side-effects caused by widely-used pharmaceuticals. Examples include the acute nephrotoxicity and irreversible ototoxicity promoted by the cationic drugs gentamicin and cisplatin. Gentamicin is an aminoglycoside antibiotic used for the prevention and treatment of life-threatening gram-negative bacterial infections, such as tuberculosis and meningitis. Cisplatin is used to treat a broad spectrum of cancers including head and neck, ovarian, cervical, stomach, bladder, sarcoma, lymphoma, testicular cancer and others.
The objective of this study is to design and synthesize rhodamine derivatives that can be used for the construction of geometrically well-defined cationic drug conjugates. The long-term goal is to use the conjugates as tools to aid in elucidating the properties and identities of ion channels involved in the uptake of cationic pharmaceuticals into kidney and cochlear hair cells. This will shed light on the origin and potential prevention of unwanted side effects such as nephrotoxicity and ototoxicity associated with specific cationic drugs.
A series of extended rhodamine analogs with reactive groups for biomolecule conjugation has been synthesized. These fluorophores show similar spectral properties to their prototype, Texas Red succinimidyl ester (TR-SE). However, they contain rigid linkers between the fluorophore and amine-reactive moiety. The resultant gentamicin conjugates of these materials are rigidified enabling one to assess channel pore dimensions without the confounding issue of conjugate folding. Preliminary cell studies are promising, as one observes reduced gentamicin uptake in both kidney and sensory hair cell upon systematically increasing the dimension of the fluorophore. This work has enabled us to tentatively assign the maximum dilated MET channel pore size as between 1.44 nm to 1.56 nm. However, this preliminary finding, though encouraging, needs further validation via ongoing studies with larger diameter fluorophore conjugates,
A cisplatin-Texas Red conjugate has also been synthesized to enable studies of cellular uptake mechanisms. This conjugate preserves not only the spectral properties of Texas Red after conjugation, but also the cytotoxicity of cisplatin. This has been validated in zebrafish. The series of rhodamine probes that have been conjugated to gentamicin should be similarly useful for cisplatin studies. These studies are planned. Additional future work includes the synthesis of semi-flexible (glycol) and flexible (alkyl) linkers to evaluate structure-activity relationships.
36
Dwyer, Suzanne. "Effects of Neonatal Clomipramine Treatment on Photic and Non-Photic Circadian Phase Shifting in Rats". Fogler Library, University of Maine, 2000. http://www.library.umaine.edu/theses/pdf/DwyerSM2000.pdf.
37
Suleiman, Abdulqadir M. "Economic and Strategic Consequences For SMEs in Norway Following Implementation of the New EU Chemicals Legislation, REACH". Thesis, Blekinge Tekniska Högskola, Sektionen för management, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-1112.
Abstract (sommario):
On the last day of May 2008, new chemicals legislation, REACH came into force in Norway following its implementation within the EU in 2007. The regulation streamlines and improves an earlier legislative framework for chemicals of the European Union. To be able to comply with the new regulation, enterprises will have to put in place considerable measures and undertake possibly restructuring part of or the entire enterprise. Such measures could include the need for training, external consultancy and need for new practical software. Other measures include strategic changes in the enterprises such as the centralization of operations, change of short/long term plans, venturing into areas, change in procurement procedures etc. These may vary from enterprise to enterprise depending on their position on the supply chain as defined by the new legislation. Importers and producers of chemicals have more duties under REACH than downstream users and distributors. This study investigates how small and medium-sized enterprises (SMEs) within the chemical industry in Norway have been affected by the implementation of the legislation; the main focus of the study is on the economic and strategic effects of REACH on SMEs. Most SMEs in Norwegian chemical industry fall under REACH’s definitions of downstream users and distributors meaning they have fewer duties compared to producer and importers. Despite fewer duties, the effect of REACH on SMEs is quite comprehensive and far-reaching.Address: Austadvn 99 3034 Drammen Tel: +47-90949602
38
Giantsos, John. "The effects of trade policy on the development of the South African petrochemical industry". Thesis, Rhodes University, 1995. http://hdl.handle.net/10962/d1002749.
Abstract (sommario):
The objective of the research was to determine the role which South African trade policy played in shaping the development of the domestic petrochemical industry. The focus of the study falls on the domestic development of the petrochemical industry in general, and the polymer industry in particular. Three broad stages are distinguished in the domestic development of the petrochemical industry. Prior to the early 1970's development occurred primarily on an ad hoc basis, with the establishment of domestic production plants for most major petrochemicals. The development of the domestic petrochemical industry over the period from the early 1970's to the early 1980's was characterised by rapid growth in the domestic production of petrochemicals, while the period from the early 1980's to the early 1990's saw a significant slowdown in the annual growth rate for the domestic production of petrochemicals. The role of trade policy in the industry's development over each of these three periods could not be established conclusively. In each period a number of factors were identified which may have impacted on the industry's development. However, two factors do appear to have played particularly important roles in the industry's development prior to the early 1980's, namely strong growth in domestic petrochemical demand and the provision of a substantial degree of protection through quantitative import controls and tariffs. with regard to the industry's development over the period from the early 1980's to the early 1990's, a number of factors were identified which may have influenced trends in domestic petrochemical production, including the withdrawal of quantitative import controls and the progressive lowering of import tariffs, the depreciation of the rand in the mid-1980's, a slowdown in the growth of the domestic demand for petrochemicals, the fall in the international prices of petrochemicals in the early 1980's, and the fall in the international oil price in the mid-1980's. In view of the small size of the domestic petrochemical market it is recommended that local petrochemical producers should continue to expand their focus beyond that of producing solely for the requirements of the domestic market. In light of the key role played by the petrochemical industry in a modern economy, it is also recommended that the industry in South Africa receive more attention from policy makers than it has in the past.
39
Xu, Zhen. "Environmental toxicity testing of chemicals : application of higher plants as test organism to investigate phytotoxic effects /". Aachen : Shaker, 2004. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=012998832&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
40
Jobling, Susan. "Environmental oestrogenic chemicals and their effects on sexual development in male rainbow trout (Oncorhynchus mykiss Walbaum)". Thesis, Brunel University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262498.
41
Maunder, Richard. "Effects of juvenile exposure to endocrine disrupting chemicals on reproductive performance in the three-spined stickleback". Thesis, Brunel University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439790.
42
Sumida, Kayo. "Development of in vitro methods for detecting the effects of various chemicals on the hormone receptors". Kyoto University, 2004. http://hdl.handle.net/2433/148340.
43
何國雄 e Kwet-heung Ho. "The vascular effects of endotoxin, cardiotoxin and tetrandrine: their actions on cell calcium". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31215270.
44
Allison, Edwin. "Effects of seed adjuvants on germination and development of onions". Thesis, Cape Technikon, 2001. http://hdl.handle.net/20.500.11838/2000.
Abstract (sommario):
Thesis (MTech (Agriculture))--Cape Technikon, 2001.Onion seeds (cultivar Caledon Globe), and soil into which the seedlings were planted, were treated with various adjuvants including fungicides, a seed disinfectant and a soil sterilant, as well as soil-applied growth stimulants to determine the effect of these on germination of seed, the growth of plants and the storage life of onions obtained. Three sets of germination trials were undertaken in petri dishes, and sets of seed was also sown in deep seed trays. A trial planting was made and the crop graded and stored. Seed was also sown in pots in soil obtained from a commercial undertaking where poor germination had been obtained. A portion of this soil was pasteurised and a portion inoculated with Fusarium spp. Growth of these seedlings was then followed by re-sowing in the same pots using seed of additional cultivars.
45
Roberts, Destiny. "The Effects of Chronic Alcohol Consumption on Ovarian Function/ Morphology". Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/honors/425.
Abstract (sommario):
Chronic alcohol (ethanol) consumption has been known to affect the major organs of the body and particularly the liver. However, the effects of chronic ethanol consumption on the female reproductive system remain relatively unstudied. A convenient way to study these effects is by analyzing laboratory mice that have been fed an ethanol diet for an extended period of time and comparing them to control mice. In this study, female mice were separated into control and ethanol fed groups. The mice were placed on their specified diets and observed over the course of six weeks. The mice were fed and weighed daily throughout the duration of the experiment. Once a week, vaginal washes were performed on both groups of mice to determine the stage of the estrous cycle for each mouse. At the end of the six weeks, the mice were sacrificed and the ovaries were harvested and fixed in 4% paraformaldehyde. The ovaries were then paraffin embedded and sectioned. Glass microscope slides were then stained using Hematoxylin and Eosin staining procedures for evaluation using standard light microscopy. The tissue’s morphology, follicle development, presence of corpora lutea, and overall appearance were analyzed. Due to the premature deaths of several mice in first group of ethanol fed mice, the experiment was repeated with three more groups of mice to obtain a better representation of data. The data from the control group was compared to that of the ethanol fed group. The mice that received the ethanol fed diet ceased to cycle and arrested in the diestrous phase of the estrous cycle. Our data indicates that the ovarian follicles within the ethanol fed mice show signs of degeneration in the 4b, 5a, 5b, 6, and 7 levels of development. There are also no notable corpora lutea present within the ovaries of the ethanol fed mice. Our findings indicate that chronic alcohol consumption has deleterious effects on ovarian morphology in mice.
46
Wallhead, Matthew W. "Foliar Fungicide Effects on Gray Leaf Spot and Yield of Hybrid Corn as Influenced by Application Timing, Hybrid Characteristics and Production Practices". The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1324573828.
47
Dodds, Darrin Matthew. "Adjuvant effects on herbicide absorption and translocation". Diss., Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-11022007-143506.
48
Lee, Nathan Robert William. "Long Term Glyphosate Effects on Roundup Ready Soybean Rhizosphere Microorganisms". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1525689141453883.
49
Dean, Timothy Neal. "The immunotoxic effects of aldicarb". Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/41612.
50
Valvi, Damaskini 1983. "Effects of endocrine disrupting chemicals on childhood growth and obesity : evidence from the Spanish INMA Birth Cohort Study". Doctoral thesis, Universitat Pompeu Fabra, 2014. http://hdl.handle.net/10803/320194.
Abstract (sommario):
Acumulada evidencia en estudios experimentales sugiere que la exposición a contaminantes capaces de interrumpir el sistema endocrino podría alterar las vías moleculares de los procesos de regulación hormonal y epigenética que están involucrados en el desarrollo del tejido adiposo y la homeostasia energética, lo que incrementaría la susceptibilidad de los individuos a ser obesos. La evidencia de esta emergente “Hipótesis de los Obesógenos Ambientales” en estudios humanos es escasa y se basa mayoritariamente en datos transversales. Por este motivo, el objetivo principal de la presente tesis fue evaluar los efectos de la exposición prenatal a compuestos orgánicos persistentes (COPs) y a los compuestos orgánicos no persistentes, BPA y ftalatos, en el crecimiento y la obesidad durante la infancia. Los datos que se utilizaron en esta tesis provienen del estudio poblacional de cohortes de nacimiento en España “Infancia y Medio Ambiente”-INMA. Los hallazgos sugieren que la exposición prenatal a COPs, ftalatos y de forma menos evidente a BPA, podrían influir en el crecimiento y la obesidad durante la infancia y que el sentido de estas asociaciones puede diferir según el contaminante y el sexo del niño.A growing body of experimental evidence suggests that exposure to endocrine disrupting chemicals during the critical windows of development may alter the molecular pathways that underlie the hormonal and epigenetic regulation of adipose tissue development and energy homeostasis and thus, may increase individuals susceptibility towards obesity. Human evidence supporting this emerging “Environmental Obesogen Hypothesis” is still scarce and largely relies on cross-sectional data. Thus, the main scope of the present thesis was to prospectively evaluate the influences of prenatal exposures to persistent organic pollutants (POPs) and the non-persistent organic pollutants, BPA and phthalates, on childhood growth and obesity. Data used in this thesis come from the population-based INMA-“INfancia y Medio Ambiente” Birth Cohort Project in Spain. Findings suggest that prenatal exposures to POPs, phthalates and less clearly BPA may influence childhood growth and obesity and that the direction of the effects may differ according to the chemical tested and child sex.