<p>'Endocrine disrupting chemicals (EDCs) are compounds found in the environment that have the potential to disrupt normal endocrine function. Estrogenic EDCs (e-EDCs) is a subclass of EDCs and is defined as substances contaminating the environment that may mimic or inhibit the effect of endogenous estrogen and therefore may influence developmental and reproductive health in humans and animals. The aim of this study was to develop, validate and implement a battery of in vitro and in vivo screening assays for e-EDCs. The study was concluded by implementing this battery of assays to assess the Eerste River, South Africa at three sampling sites, namely Jonkershoek, Stellenbosch sewage treatment works (STW) effluent and Spier for e-EDCs. The control site, Jonkershoek contained very low levels of estrone. Water from this site showed no estrogenic activity when the E-screen and the ER_ induction in MCF-7 cells. Some of the water samples collected at this site tested positive for estrogenicity when analysed with the juvenile tilapia VTG assay, whereas the rest were negative. The estrone levels in the sewage effluent extracts as well as Spier were significantly higher. The assay using ER_ protein induction by the MCF-7 cell line, the MCF-7 proliferation assay and the tilapia in vivo screen for estrogenicity showed that these samples are estrogenic. Results obtained for estrogenicity at the three different sampling sites for each of the assays in the battery were comparable. In this study we developed, validated and also implemented a battery of assays encompassing both in vitro and in vivo assays, based on different biological mechanisms, to detect estrogenic EDCs. To our knowledge, this is the first study that has used a battery of bioassays to specifically assess a South Africa river for estrogenicity...'</p>

Thesis (Ph. D.)--University of Hong Kong, 1987.

<p>'Endocrine disrupting chemicals (EDCs) are compounds found in the environment that have the potential to disrupt normal endocrine function. Estrogenic EDCs (e-EDCs) is a subclass of EDCs and is defined as substances contaminating the environment that may mimic or inhibit the effect of endogenous estrogen and therefore may influence developmental and reproductive health in humans and animals. The aim of this study was to develop, validate and implement a battery of in vitro and in vivo screening assays for e-EDCs. The study was concluded by implementing this battery of assays to assess the Eerste River, South Africa at three sampling sites, namely Jonkershoek, Stellenbosch sewage treatment works (STW) effluent and Spier for e-EDCs. The control site, Jonkershoek contained very low levels of estrone. Water from this site showed no estrogenic activity when the E-screen and the ER_ induction in MCF-7 cells. Some of the water samples collected at this site tested positive for estrogenicity when analysed with the juvenile tilapia VTG assay, whereas the rest were negative. The estrone levels in the sewage effluent extracts as well as Spier were significantly higher. The assay using ER_ protein induction by the MCF-7 cell line, the MCF-7 proliferation assay and the tilapia in vivo screen for estrogenicity showed that these samples are estrogenic. Results obtained for estrogenicity at the three different sampling sites for each of the assays in the battery were comparable. In this study we developed, validated and also implemented a battery of assays encompassing both in vitro and in vivo assays, based on different biological mechanisms, to detect estrogenic EDCs. To our knowledge, this is the first study that has used a battery of bioassays to specifically assess a South Africa river for estrogenicity...'</p>

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 10 uppsatser.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1947. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 73-87).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1942. / Typescript. Includes abstract and vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 37).

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Philosophiae Doctor - PhD / Endocrine disrupting chemicals (EDCs) are compounds found in the environment that have the potential to disrupt normal endocrine function. Estrogenic EDCs (e-EDCs) is a subclass of EDCs and is defined as substances contaminating the environment that may mimic or inhibit the effect of endogenous estrogen and therefore may influence developmental and reproductive health in humans and animals. The aim of this study was to develop, validate and implement a battery of in vitro and in vivo screening assays for e-EDCs. The study was concluded by implementing this battery of assays to assess the Eerste River, South Africa at three sampling sites, namely Jonkershoek, Stellenbosch sewage treatment works (STW) effluent and Spier for e-EDCs. The control site, Jonkershoek contained very low levels of estrone. Water from this site showed no estrogenic activity when the E-screen and the ER_ induction in MCF-7 cells. Some of the water samples collected at this site tested positive for estrogenicity when analysed with the juvenile tilapia VTG assay, whereas the rest were negative. The estrone levels in the sewage effluent extracts as well as Spier were significantly higher. The assay using ER_ protein induction by the MCF-7 cell line, the MCF-7 proliferation assay and the tilapia in vivo screen for estrogenicity showed that these samples are estrogenic. Results obtained for estrogenicity at the three different sampling sites for each of the assays in the battery were comparable. In this study we developed, validated and also implemented a battery of assays encompassing both in vitro and in vivo assays, based on different biological mechanisms, to detect estrogenic EDCs. To our knowledge, this is the first study that has used a battery of bioassays to specifically assess a South Africa river for estrogenicity. / South Africa

Young, middle-aged and old rat adrenal gland steroidogenesis was measured in isolated, superfused glands and in their subcellular fractions before and after adrenocorticotropic hormone treatment. In the latter experiment, five corticosteroids were extracted from six different subcellular fractions. Superfused glands initially produced relatively high glucocorticoid levels; thereafter, production decayed asymptotically. Steroidogenesis by young and middle-aged glands was maintained at least 1.5 to 2.5 hours before it decayed; old glands were 50% less active than younger ones and production decayed within one hour. High cholesterol and progesterone levels in certain old gland fractions were associated with correspondingly reduced 11-deoxycorticosterone and corticosterone. It is suggested that synthesis of these glucocorticoids from their accumulating precursors weakens with age.

Male ring doves ( Streptopelia risoria ) held on long days perform more nest-building than birds held on short days. This difference persists even if circulating androgen is maintained at similar levels in both groups by castration and treatment with exogenous testosterone. It therefore appears that daylength can alter nest-building through some means other than changes in gonadal androgen production. The experiments described in this thesis examined three mechanisms which might be responsible for the effect of daylength on male nest-building. The first series of experiments tested the hypothesis that nest-building activity is greater under long days as a result of increased aromatization of testosterone into estrogen. Castrated male doves were implanted with estradiol benzoate, testosterone propionate (TP), or a combination of TP and an aromatase inhibitor, ATD, and exposed to either long or short photoperiods. Males held under long days continued to build more actively, regardless of the type of hormone being used. The results thus indicate that differences in the rate of aromatization cannot account for the effect of photoperiod. In a second series of experiments an attempt was made to determine whether an increase in the production of hypothalamic luteinizing hormone releasing hormone (LHRH) under long daylengths stimulates nest-building, as a result of a synergism with testosterone. Long- and short-day castrated males were treated with exogenous TP or TP and LHRH to see if the influence of short daylengths could be reversed by LHRH. LHRH treatment had no effect on the nesting activity of either short- or long-day birds. Finally, several tests were performed which focussed on the role of the pineal gland. Removal of the pineal caused a decrease in nesting activity in long-day birds, but not in short-day birds. The effect of pinealectomy does not depend on the presence of the gonads, since the birds displayed similar responses following castration and testosterone treatment. In the second test, the ability, of pinealectomy to nullify the stimulatory influence of long daylengths was confirmed. In addition, injections of chicken pineal extract increased nest-building in pinealectomized and in short-day pineal-intact birds, suggesting that the pineal produces a substance which is capable of stimulating nesting activity. The identity of this substance is unknown. Pilot tests using melatonin failed to show any stimulatory effect of this compound on nesting behaviour. However, serotonin, which is also present in the pineal in high concentration, did increase nest-building in short-day pinealectomized males. These results indicate that in response to long daylengths the pineal gland of male doves releases a compound, possibly serotonin, which stimulates nest-building activity. / Science, Faculty of / Zoology, Department of / Graduate