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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.
21

Effects of Developmental Exposures of Two Emerging Environmental Toxicants on Estrogen-Sensitive Endpoints

Hill, Corinne E 17 July 2015 (has links)
Thousands of synthetic chemicals have been released into the environment, causing widespread exposures of wildlife and humans alike. Some of these chemicals are known to disrupt aspects of hormone action thus inducing abnormalities in endocrine tissues and organs. Bisphenol S (BPS) and tetrabromobisphenol A (TBBPA), two largely unstudied chemicals commonly used in consumer products, are suspected to have endocrine disrupting properties based on their similar chemical structures to known endocrine disrupting chemicals (EDCs). To determine whether developmental exposure to BPS or TBBPA induced abnormalities in the ovary, mice were administered oil, BPS or TBBPA during pregnancy and lactation. The ovaries of female offspring were examined for gross morphological, immunohistological and gene expression differences at postnatal day (PND) 22 and week 16. To determine whether these exposures alter responses to hormones, two females from each litter were administered either oil or ethinyl estradiol (EE2) from PND 19-21. Our study identified significant differences in ovarian follicular formation and gene expression after developmental TBBPA and BPS exposures. Most effects were observed at PND22 (pre-puberty), and were apparent after the EE2 challenge, suggesting that changes induced by BPS and TBBPA are age- and hormone- dependent. Our results are consistent with the hypothesis that TBBPA and BPS are EDCs; that these compounds can disrupt development of the ovary; and that the observed effects of TBBPA and BPS exposure are similar to risk factors for ovarian diseases including cancer. These findings may indicate that widespread exposures to BPS and TBBPA could have implications for public health.
22

End Use Packaging: A Survey of Customer Perception of Recycling and Environmental Impact of Packaging Materials

Lamb, Whitney Chelsea 05 May 2012 (has links) (PDF)
Studies have shown that traditional food packaging for the fast food industry leach toxic chemicals into the food products. Some of these toxins are known endocrine disruptors, which results in reproductive issues as well as hormone imbalances. Alternatives to traditional food packaging have been addressed with special attention to bioactive, biopolymers, and biodegradable packaging in addition to active and intelligent packaging. The hypothesis states that customers will have high demand for more environmentally sustainable fast food packaging, while the alternative hypothesis states that demand will not be high enough to financially support the costly introduction of more environmental packaging products. The data attained suggest that the hypothesis will not be rejected. However, there are not conclusive results in terms of the alternative hypothesis, as further studies that address economical concerns must be completed. In terms of consumer demand, 94.92% preferred environmentally sustainable packaging over traditional packaging materials.
23

Impact of an atrazine-based herbicide on an agrobiont wolf spider

Godfrey, Jake A. 29 September 2017 (has links)
No description available.
24

Reduction of Perchlorate from Contaminated Waters Using Zero Valent Iron and Palladium under UV Light

Zhao, Qiuming 20 April 2011 (has links)
No description available.
25

Dietary intake estimations of brominated flame retardants for Swedish children

Lindström, Jonna January 2008 (has links)
<p>The dietary intake of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD) have been estimated for Swedish children. A dietary survey performed in 2003, including 4, 8-9 and 11-12 year olds, and concentrations in individual food items were combined. The food included in the study was mainly of animal origin, consisting of fish and shellfish, dairy products, meat products, eggs, animal and vegetable fats and fats from miscellaneous food products. The medium-bound intake of PBDEs (9 congeners) were estimated to 23.0 ng/day, 30.9 ng/day and 27.7 ng/day for 4, 8-9 and 11-12 years olds respectively. The corresponding estimations for HBCD were 7.94 ng/day 10.7 ng/day and 9.46 ng/day for 4, 8-9 and 11-12 years olds respectively. These results show a higher daily intake for 8-9 year olds compared with the other age groups. However, when estimating the daily intake per kg bw, the intake decreases with age. BDE-47 contributed the most to the total intake of PBDEs, with approximately 40%. The food group contributing the most to the intake of PBDEs and HBCD was fish and shellfish, of which non-Baltic fatty fish was the largest contributor. There were no considerable differences between boys and girls in any of the aspects examined. The result from this study show a lower intake of PBDEs and HBCD in Swedish children compared with children in other studies made in Europe and the United States.</p> / <p>Bromerade flamskyddsmedel används för att skydda brännbara material från att fatta eld, till exempel skyddas textilier och plaster i bland annat elektronik, fordon och möbler. Två typer av bromerade flamskyddsmedel är polybromerade difenyletrar (PBDE) och hexabromocyklododekan (HBCD). Dessa är additiva flamskyddsmedel och blandas i materialet som ska skyddas men binder inte in i produkten och kan därför lätt läcka ut i miljön, vilket också har skett. Halter har påträffats i miljön och i biota långt från plaster där ämnena produceras eller används.</p><p>PBDE och HBCD har visats ha hormonstörande och neurotoxiska effekter i studier på råtta och mus. Thyroxinnivåerna sjunker vid exponering av PBDE och HBCD, vilket skulle kunna leda till sköldkörtelproblem och störd utveckling av bland annat hjärnan om exponering sker perinatalt. De neurotoxiska effekterna inkluderar inlärnings- och minnessvårigheter och ett förändrat beteende med hyper- och hypoaktivitet som följd.</p><p>Human exponering för PBDE och HBCD sker främst via födan och speciellt via animaliska produkter då dessa ämnen är lipofila, bioackumulerande och ofta biomagnifierande vilket gör att de påträffas i högre koncentrationer högre upp i trofinivåerna. Studier från bland annat Sverige och Finland visar att fisk och skaldjur är den största källan till intag av PBDE.</p><p>De flesta intagsberäkningar av PBDE och HBCD baseras på livsmedelskonsumtionen hos vuxna och visar följaktligen endast hur intaget ser ut för den delen av populationen. För barn, som är en av de känsligaste grupperna i populationen, finns inte många studier att tillgå, varken från Sverige eller andra delar av världen. I den här studien har därför intaget av PBDE (summan av 9 kongener) och HBCD beräknats för barn i Sverige.</p><p>I en rikstäckande kostundersökning utförd 2003 deltog barn i åldrarna 4, 8-9 och 11-12 år. De fick i en matdagbok ange sin konsumtion under fyra på varandra följande dagar. Data från denna undersökning kombinerades sedan med haltdata från olika livsmedel för att räkna ut intaget av PBDE och HBCD på individbasis. Undersökningen innefattade främst animaliska livsmedel och innehöll därför fisk och skaldjur, mejeriprodukter, köttprodukter, ägg, animaliskt och vegetabiliskt fett och fett från övriga livsmedel.</p><p>Resultaten visar att födointaget av PBDE var 23,0 ng/dag, 30,9 ng/dag och 27,7 ng/dag för 4, 8-9 respektive 11-12 åringar. Intaget av HBCD beräknades till 7,94 ng/dag, 10,7 ng/dag och 9,46 ng/dag för 4, 8-9 respektive 11-12 åringar. Detta visar att 8-9 åringar har det högsta dagliga intaget av PBDE och HBCD. När intaget beräknas på kroppsvikt däremot, har de yngsta barnen det högsta intaget som sedan sjunker med åldern. Fisk och skaldjur var den största källan till intaget av PBDE och HBCD, trots att konsumtionen av dessa livsmedel var relativt lågt. Det fanns ingen större skillnad mellan pojkar och flickor, varken i intag av PBDE eller av HBCD. Jämfört med de få studier som gjorts i andra länder, är det tydligt att svenska barn har ett lägre intag av PBDE och HBCD.</p><p>Undersökningen tyder också på att intaget av PBDE och HBCD hos svenska barn, utifrån de kunskaper vi har idag, inte utgör någon risk med avseende på de effekter av PBDE och HBCD som påträffats i toxikologiska studier. Däremot är barn i ett känsligt skede i livet och upprepad exponering samt exponering för flera miljögifter samtidigt skulle kunna påverka deras utveckling negativt.</p>
26

Caractérisation des cellules gliales olfactives associées aux neurones à GnRH-I : rôle dans le développement de ces neurones / Characterization of olfactory glial cells associated with GnRH neurons-1 : role in GnRH-1 neurons development

Geller, Sarah 18 April 2013 (has links)
Chez le mammifère la fonction de reproduction est sous le contrôle des neurones hypothalamiques à GnRH-I. Au cours du développement embryonnaire ces neurones migrent de la fosse nasale vers le cerveau. De nombreuses études s’intéressent aux facteurs impliqués dans leur migration, mais l’influence de leur environnement cellulaire est très peu étudiée. Nous avons émis l’hypothèse que les neurones à GnRH-I d’origine extra-cérébrale possèdent un environnement gliale nécessaire à leur migration, connaissant le rôle de ces cellules dans l’ontogenèse neuronale du cerveau. Nos résultats montrent que 1) les neurones à GnRH-I sont associés à des cellules gliales au cours de leurs migrations nasale et télencéphalique 2) ces cellules gliales sont des progéniteurs des cellules gliales olfactives engainantes qui se différencient dans les régions rostrales au cours de la migration neuronale. 3) ces cellules expriment des gènes codant pour des facteurs impliqués dans la migration de ces neurones. 4) le transcriptome de ces cellules gliales est perturbé en présence d’un perturbateur endocrinien œstrogèno-mimétique, et touche des familles de gènes impliquées dans les molécules d’adhésions cellulaires nécessaire à la migration et à la régulation de l’activité des neurones à GnRH-I. / GnRH-I cells control reproduction functions in mammals. These cells are extra cerebral since they come from the nasal pit and migrate to the forebrain during embryonic development. Numerous studies have described the influence of different molecules on the migration of GnRH-1 neurons, however, the role of microenvironment cells remains poorly understood. Considering the role of glial cells in the forebrain’s neuronal migration, we had hypothesized that extra-cerebral GnRH-I neurons possess a glial environment necessary for their migration from the nose to the brain. Our results demonstrated that 1) GnRH-I neurons are associated with glial cells during their migration in the nasal septum and forebrain 2) These glial cells are progenitors of olfactory ensheathing cells, and differentiated within the rostral regions during neuronal migration. 3) These cells express genes encoding factors involved in GnRH-I neurons migration 4) Glial cells transcriptome are disrupted with estrogen-mimicking endocrine disruptor, and affects gene families involved in cell adhesion molecules necessary for migration and activity regulation of GnRH-I neurons
27

Vliv vybraných endokrinních disruptorů na lidskou spermatogenezi / The Impact of Selected Endocrine Disruptors on Human Spermatogenesis

Vítků, Jana January 2016 (has links)
Steroid hormones in testis play an important role in spermatogenesis, maintenance of the male reproductive tract, production of semen and the maintenance of secondary sex characteristics and libido. They are also discussed as a target for substances called endocrine disruptors (EDs). No complex study was conducted on evaluation of relationships between EDs and steroid spectrum in 2 biological fluids; seminal plasma and plasma. The aim of the PhD. thesis was to develop and validate a method for determination of bisphenol A (BPA) and steroid spectrum in plasma and seminal plasma and to shed more light into mechanisms of ED action and effects of BPA and polychlorinated biphenyls (PCBs) on human spermatogenesis and steroidogenesis. Two new liquid-chromatography mass spectrometry methods for determination of BPA and 11 steroids in plasma and seminal plasma were developed and validated. The methods were used for estimation of analyte concentrations in 191 men with a different degree of fertility. Concurrently, the levels of six congeners of PCBs, gonadotropins, selenium and zinc in plasma were estimated. Partial correlations adjusted for age and BMI were calculated to evaluate relationships between these analytes. Seminal BPA, but not plasma BPA, was negatively associated with sperm concentration...
28

Effets biologiques et mécanismes d'action de ligands environnementaux du récepteur nucléaire de la progestérone chez le poisson zèbre / Modes of action and biological effects of environmental ligands of the nuclear progesterone receptor in zebrafish

Garoche, Clémentine 04 October 2017 (has links)
Chez les vertébrés, la progestérone (P4) est un progestatif endogène agissant via les récepteurs nucléaires et membranaires de la progestérone pour médier des processus clés du développement et de la reproduction. De nombreuses molécules sont conçues pour mimer l’action de la P4. Ces progestatifs synthétiques et la P4 sont très utilisés en tant que substances pharmaceutiques et certains sont retrouvées dans l’environnement aquatique, posant un risque pour les organismes. Cependant, les informations sont insuffisantes pour évaluer les dangers et les risques de ces substances pour l’environnement. Dans ce travail de thèse, les mécanismes d’action et les effets biologiques des progestatifs sur le poisson zèbre ont été étudiés grâce à une combinaison d’outils in vitro et in vivo de type gène-rapporteur basés sur le mécanisme d’action des perturbateurs endocriniens. Nous avons caractérisé le profil toxicologique complexe de 26 progestatifs vis-à-vis de différents récepteurs nucléaires stéroïdiens humain et poisson zèbre et vis-à-vis de l’expression tissu-spécifique de gènes de la stéroïdogenèse (cyp19a1b dans le cerveau et cyp11c1 dans les interrénales). Nos résultats montrent que certains progestatifs peuvent perturber différentes voies de signalisation chez les larves en développement au niveau moléculaire, cellulaire et tissulaire ainsi qu’au niveau physiologique. Dans l’ensemble, les résultats de cette thèse permettent une meilleure caractérisation des dangers des progestatifs sur différentes cibles endocriniennes. / Among vertebrates, progesterone (P4) is an endogenous progestin acting through the nuclear and molecular progesterone receptor to mediate key processes of development and reproduction. Many molecules are designed to mimic the action of P4. These synthetic progestins and P4 are widely used as pharmaceuticals and some of them are found in this aquatic environment, thus posing risks to aquatic species. However, information is lacking to evaluate the dangers and risks of these substances for the environment. This thesis studied the mechanisms of action and the effects of progestins on zebrafish, using a combination of reporter-gene in vitro and in vivo tools based on the mechanism of action of endocrine disruptors. We characterized the toxicological profile of 26 progestins towards different human and zebrafish nuclear steroid receptors and towards the tissue-specific expression of steroidogenic genes (cyp19a1b in the brain and cyp11c1 in the interrenal cells). Our results show that some progestins can disrupt different signaling pathways in developing larvae at the molecular level, cellular and tissular level, and physiological level. Overall, the results of this thesis allow for a better characterization of the dangers of progestins on several endocrine targets.
29

Développement de la mesure de la vitellogénine chez les invertébrés & utilisation de marqueurs de la perturbation endocrinienne chez le crustacé amphipode gammarus fossarum / Development of vitellogenin measurement in invertebrates & use of endocrine disrupting markers in the amphipod crustacea Gammarus Fossarum

Jubeaux, Guilaume 03 July 2012 (has links)
Parmi les substances polluantes, les perturbateurs endocriniens (PE) sont au coeur des préoccupations scientifiques en raison du risque de ces composés pour l'environnement, et en particulier les écosystèmes aquatiques. L'étude de la disponibilité et de l'impact des PE sur les vertébrés aquatiques, en particulier les poissons, a fait l'objet de nombreux projets et publications. Ces travaux ont conduit au développement d'outils de diagnostic pouvant être utilisés in situ, comme par exemple l'induction de la vitellogénine (Vg) chez les mâles, l'inhibition de la croissance ovarienne et testiculaire, le retard dans la maturité sexuelle, la présence d'individus intersexués et les concentrations anormales en hormones stéroïdiennes. En revanche, peu d'attention a été portée aux invertébrés qui représentent pourtant plus de 95 % des espèces animales et jouent un rôle essentiel dans le fonctionnement et la santé des écosystèmes aquatiques. Par conséquent, il en résulte un manque d'outils spécifiques de la perturbation endocrinienne chez ces espèces. Dans ce contexte, le travail proposé se focalise tout d'abord sur l'intérêt et la pertinence de la spectrométrie de masse (LC-MS/MS) pour développer ou transférer entre espèces une méthode de mesure de la Vg chez les invertébrés, incluant les crustacés, les mollusques et les insectes. Ensuite, ce travail s'est intéressé à un crustacé amphipode modèle (Gammarus fossarum) et avait pour objectifs (1) de développer le biomarqueur Vg, via la validation de son rôle fonctionnel dans la reproduction (vitellogenèse, embryogenèse et différences inter-sexe), de sa sensibilité à des composés modèles et jusqu'à son utilisation dans le cadre d'études de terrain à l'aide d'organismes encagés et (2) de développer l'utilisation d'une approche chez la femelle permettant de caractériser le potentiel PE de composés et des systèmes aquatiques, à partir de l'étude de marqueurs individuels / Among pollutants, endocrine disruptors (ED) are in central scientific preoccupation because of the risks of these compounds to the environment, in particular for aquatic ecosystems. The availability and impact study of ED on aquatic vertebrates, in particular fishes, was the subject of many projects and papers. These studies led to the development of diagnostic tools, such as vitellogenin (Vg) induction in male organisms, inhibition of ovarian and testicular growth, delayed sexual maturity, presence of intersex individuals and abnormal concentrations of steroid hormones. However, little attention was paid to invertebrates which account for more than 95% of animal species and play an essential role in functioning and health of aquatic ecosystems. Therefore, the result is a lack of specific tools for endocrine disruption assessment in these species. In this context, the proposed work focuses first on the interest and relevance of mass spectrometry (LC-MS/MS) to develop and to transfer among species a method for measuring Vg in invertebrates species, including crustaceans, molluscs and insects. Then, this work has focused on a model amphipod crustacean (Gammarus fossarum) and aims were (1) to develop the Vg biomarker, through the validation of its functional role in reproduction (vitellogenesis, embryogenesis and inter-sex differences), its sensitivity towards model compounds and to its use in field monitoring, using caged organisms and (2) develop a biotest in the female to assess the ED risk of chemical compounds and aquatic systems, by studying and measuring individual markers
30

Vliv vybraných endokrinních disruptorů na lidskou spermatogenezi / The Impact of Selected Endocrine Disruptors on Human Spermatogenesis

Vítků, Jana January 2016 (has links)
Steroid hormones in testis play an important role in spermatogenesis, maintenance of the male reproductive tract, production of semen and the maintenance of secondary sex characteristics and libido. They are also discussed as a target for substances called endocrine disruptors (EDs). No complex study was conducted on evaluation of relationships between EDs and steroid spectrum in 2 biological fluids; seminal plasma and plasma. The aim of the PhD. thesis was to develop and validate a method for determination of bisphenol A (BPA) and steroid spectrum in plasma and seminal plasma and to shed more light into mechanisms of ED action and effects of BPA and polychlorinated biphenyls (PCBs) on human spermatogenesis and steroidogenesis. Two new liquid-chromatography mass spectrometry methods for determination of BPA and 11 steroids in plasma and seminal plasma were developed and validated. The methods were used for estimation of analyte concentrations in 191 men with a different degree of fertility. Concurrently, the levels of six congeners of PCBs, gonadotropins, selenium and zinc in plasma were estimated. Partial correlations adjusted for age and BMI were calculated to evaluate relationships between these analytes. Seminal BPA, but not plasma BPA, was negatively associated with sperm concentration...

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