Corrigenda inserted behind title page. / Copies of author's previously published articles inserted at end. / Includes bibliographical references (leaves 193-210). / xxii, 210 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Investigates whether estrogen modulates the proteins associated with calcium transport (eg calcium binding protein, calbindin D28k) in the intestinal tissue during sexual maturation of laying hens. Studies the temporal and spatial expression of estrogen receptors (ER) and calcium binding protein in jejunal tissue. Findings indicated the potential of estrogen to induce calbindin D28K in the intestinal tissue, from which it can be concluded that estrogen may increase calcium absorption and consequently calcium retention. Shows that the amount of estrogen normally present in the reproductive system is sufficient for the normal capacity of egg and eggshell production. Egg production and shell quality are significantly reduced by phytoestrogen. It is recommended that the concentration of phytoestrogen in poultry diets be investigated in more detail as it may act as an anti-nutritive factor and affect metabolism and productivity. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Science, 1999

Bibliography: leaves 281-316. Presents investigations on pubertal development in South Australian merino ram lambs and examines the effect of active and passive immunizations against oestradiol-17ℓ or oestrone on testicular maturation.

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Gender has long been considered an important factor in uncovering the etiology of schizophrenia. There is now strong evidence that gender is related to the age at onset of psychotic symptoms and somewhat weaker evidence of gender differences in other aspects of schizophrenia, such as clinical and functional outcomes. Simultaneously, there is growing evidence that age at onset itself is an important prognostic factor. This dissertation seeks to investigate the complex relationship between gender, age at onset, and outcomes of schizophrenia spectrum disorders, in light of two main mechanisms, estrogen protection and psychosocial development. The estrogen protection hypothesis posits that estrogen has antipsychotic effects that result in a later age at onset and more favorable outcomes for pre-menopausal women compared with men with onset at the same age. When women lose estrogen protection around menopause, they may develop a more severe illness. The psychosocial development hypothesis posits that women who have later onset due to estrogen protection have more time to develop psychosocial resources that improve their role functioning later in life. In Chapter 2, a systematic literature review was conducted on the relationship between gender and age at onset of schizophrenia spectrum disorders in determining functional outcomes. There was some support for the psychosocial development hypothesis where age at onset mediates the relationship between gender and functional outcomes. Three studies were identified that conducted formal mediation analyses and used minimum criteria to detect mediation in the remaining studies. Together, these findings suggest that women have better functioning outcomes than men, by virtue of having later illness onset. Chapters 3 & 4 utilized a nationally representative sample of people with schizophrenia spectrum disorders in China to further examine the relationship between gender, age at onset, and other illness outcomes. Unlike many studies in the current literature, this dataset included people who had never sought formal treatment, providing a unique opportunity to explore the possibility of selection bias in other studies that primarily recruit participants from treatment settings. Furthermore, the majority of schizophrenia research has been conducted in high-income countries, and these data from China could provide some important insights from a low- to middle-income country. In Chapter 3, finite mixture techniques were used to model the entire distribution of age at onset as a function of gender and family history, taking into account any clustering patterns of observations. The analysis identified an early-onset group characterized by men and those with a family history, a mid-onset group characterized by both men and women without a family history, and a late-onset group characterized by women without a family history. Distinguishing between these groups showed that gender and family history are indeed robust predictors of age at onset. Chapter 4 investigated a) the interaction between gender and age at onset in producing clinical outcomes and b) the mediating effect of age at onset in the relationship between gender and role functioning outcomes. This study did not find evidence of interaction between gender and age at onset in producing clinical outcomes. It did find that women’s increased probability of marrying was mediated by a later age at onset. Overall, the results of this dissertation provide even further support of the well-established relationship between gender and age at onset. However, applying the estrogen protection hypothesis to schizophrenia spectrum outcomes requires further study. This dissertation also suggests that the psychosocial development hypothesis, which is not well-studied, may provide a promising new perspective on whether and why women appear to have better outcomes. This research also expands our knowledge of gender differences in schizophrenia spectrum disorders in China and highlights the importance of further research in other low- to middle-income countries. While the estrogen protection and psychosocial development hypotheses are surely important in our understanding of women with schizophrenia spectrum disorders, conducting this study using a dataset from China called attention to other social, political, and economic issues that women face that affect all aspects of their illness. These issues and their impact on women are likely different in high-income countries. Ultimately, the estrogen protection and psychosocial development hypotheses can only be understood within the complex context of women’s lived experience with schizophrenia spectrum disorders.

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Depression is a major mental health problem for women. Several lines of evidence suggest that fluctuating levels of estrogen associated with various reproductive events are related to changes in mood. It has been hypothesized that estrogen may exert its influence on mood via its effect on the serotonergic system---a system frequently implicated in the regulation of mood. The major goal of the following study was to elucidate further the role of estrogen in mood regulation. To this end, we examined the role of estrogen in the mood-lowering effect of Acute Tryptohpan Deption (ATD), a technique designed to cause a marked lowering of plasma and brain tryptophan, and therefore brain serotonin levels, so that the effects of decreased serotonin on mood can be studied directly. We hypothesized that (1) exogenous estrogen may protect against the mood-lowering effects of ATD in postmenopausal women and that (2) a history of affective disturbance, particularly reproduction-related affective disturbance, would be associated with greater vulnerability to ATD as predicted by the kindling model of depression. Fifty-eight postmenopausal women were randomly assigned to treatment with estrogen (0.625 mg Premarin) or placebo in the context of prospective, double-blind, cross-over design. During the final two week sof the 12-week treatment phase, all participants completed one ATD test session and one nutritionally balanced amino acid control session. We found that: (1) treatment with exogenous estrogen significantly improved mood and menopausal symptoms as compared to placebo treatment, (2) ATD was associated with a significant lowering of mood in both groups, (3) treatment with estrogen did not protect women from ATD effects unless they responded to 11 weeks of treatment with exogenous estrogen with enhanced mood, and (4) a history of reproduction-related affective disturbance was associated with more dysphoric mood in response to ATD. In conclusion, these data provide further evi

Dissertation (PhD)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Concern has increased that widespread adverse effects are occurring in humans and wildlife populations as a result of exposure to environmental chemicals (mostly man-made) that disrupt the normal functioning of the endocrine system. Many pharmaceutical, agricultural and industrial chemicals, acting as endocrine modulating compounds (EDCs), have been detected in an accumulated form in food, in drinking water and in the environment. Although the levels of these chemicals can be measured analytically, it is important to evaluate biological activity. For this, animal models are used and relevant bioassays developed. These assays are based on biological markers, which are specific xenobiotically-induced physiological responses and are usually deviations in cellular or biochemical components, processes or structures. Vitellogenin is a large protein complex, produced in the liver under estrogen control and circulates in the plasma, destined for incorporation into the developing oocyte in female oviparous vertebrates. Since vitellogenin production is low or nonexistent in males, its presence may therefore be interpreted as evidence of exposure to estrogenic environmental contaminants. In this study the African Clawed Frog, Xenopus laevis was used as model to study the effects of estrogens on biochemical and physiological parameters associated with vitellogenesis. As a starting point the seasonal female reproductive cycle in a natural Xenopus laevis population in terms of ovarian state, plasma vitellogenin and plasma estrogen levels was studied. It was shown that plasma vitellogenin and estrogen levels were seasonal and correlated to a seasonal ovarian cycle, which peaked during spring. However, although seasonality existed, there were reproductively active individuals at any time during the year. Increases in plasma estrogen levels predated increases in plasma vitellogenin levels and ovarian maturation. Lipoprotein profiles, as well as plasma cholesterol, triglyceride and phospholipid concentrations were determined and it was shown that estrogen affected these in such a way that these parameters could be used as additional markers in estrogen contamination studies. In order to develop an in vitro bioassay to screen for estrogenic activity, the use of hepatic tissue cultures was investigated. Optimal culture conditions were established and increased sensitivity in the estrogenic response was obtained by using liver slices from male frogs that were pre-treated with estrogen. Validation studies proved that this bioassay could be employed for routine screening of water and chemical samples. In order to refine the Xenopus laevis vitellogenin ELISA and liver slice bioassay, existing polyclonal anti-vitellogenin antibodies were replaced by culturing monoclonal antibodies. Selected antibodies were characterised and ELISAs developed and validated. This study showed that the newly developed Xenopus laevis vitellogenin ELISA and liver slice bioassay have the potential to be employed in environmental monitoring programmes. / AFRIKAANSE OPSOMMING: Daar is toenemende besorgdheid dat afwykings in mens- en dierbevolkings voorkom as gevolg van blootstelling aan chemikalieë (hoofsaaklik mensgemaak) in die omgewing wat die normale werking van die endokrienstelsel versteur. Verskeie farmaseutiese, landbou- en industriële chemikalieë, wat as endokrienversteurders optree, is in die omgewing gevind. AI kan die vlakke van hierdie stowwe analities bepaal word, is dit belangrik om hulle biologiese aktiwiteit te evalueer. Hiervoor word diermodelle aangewend om toepaslike toetse daarvoor te ontwikkel. Hierdie toetse word baseer op biologiese merkers, spesifieke xenobioties-geïnduseerde fisiologiese reaksies, en is gewoonlik afwykings van sellulêre- of biochemiese komponente, -prosesse of - strukture. Vitellogeen ('n dooiervoorloper) is 'n lipoproteïenkompleks wat, onder estrogeenbeheer, in die lewer vervaardig word en in die plasma sirkuleer vir uiteindelike inkorporasie in ontwikkelende oësiete van vroulike, ovipare werweldiere. Aangesien daar min of geen vitellogeen in manlike diere geproduseer word, is die teenwoordigheid daarvan 'n aanduiding dat die dier aan estrogeniese omgewingsbesoedeling blootgestel is. In hierdie studie is die Platanna, Xenopus laevis, as model gebruik om die gevolge van estrogene op biochemiese en fisiologiese veranderlikes, wat met vitellogenese geassosieer word, te bestudeer. As vertrekpunt is die seisoenale voortplantingsiklus van die wyfie, in terme van vitellogeen en -estrogeen vlakke in die plasma en aktiwiteit van die ovaria bepaal. Daar is aangetoon dat die estrogeen- en vitellogeenvlakke in die plasma met die ovariumsiklus, wat gedurende die lente hoogtepunte bereik, korreleer. Alhoewel daar seisoenaliteit bestaan, was daar dwarsdeur die jaar wyfies wat ovarium dooierneerlegging getoon het. Verhoging in estrogeenvlakke het vitellogeenpieke en rypwording van die ovaria voorafgegaan. Lipoproteïenprofiele, sowel as die cholesterol- , trigliseried- en fosfolipiedkonsentrasies in die plasma is bepaal en daar is aangetoon dat estrogeen hierdie medeveranderlikes in só 'n mate affekteer dat hulle as bykomende biomerkers vir estrogeenblootstelling in besoedelingstudies gebruik kan word. In vitro Xenopus laevis lewersnitte in die weefselkultuur omgewing is ondersoek om 'n biotoets te onwikkel vir die gebruik in vinnige estrogenisiteits-toetsing van watermonsters en chemise stowwe. Die mees gunstige kultuurtoestande is bepaal en die sensitiwiteit van estrogeenreaksies is verhoog deur lewer van mannetjies, wat vooraf met estrogeen behandel is, te gebruik. Hierdie biotoets se geldigheid is gestaaf en kan in roetine eerstevlaktoetsing van watermonsters gebruik word. Die gebruik van poliklonale teenliggaampies in 'n bestaande enzyme-linked immunosorbent assay (ELISA) is vervang deur spesiaal-ontwikkelde monoklonale anti-Xenopus laevis vitellogeen teenliggaampies. Uitgesoekte teenliggaampies, spesifiek teen die estrogeengeïnduseerde proteïene, is gekarakteriseer en ELISAs saamgestel en die geldigheid gestaaf. Hierdie studie het aangetoon dat die nuut-onwikkelde Xenopus laevis vitellogeen-ELISA en lewerkultuurbiotoets die potensiaal het om In omgewingsmoniteringprogramme gebruik te word.

Chronic treatment with enalapril and valsartan significantly improved endothelium-dependent relaxations of aortas from ovariectomized rats. The present results clearly point to that chronic treatment with enalapril or valsartan reduced expression and function of RAS and associated oxidative stress, thereby augmented NO bioavailability and improved endothelium-dependent relaxations. These results provided novel evidence supporting a potential application of ACEI and ARB in the treatment of endothelial dysfunction-associated vascular complications in postmenopausal women. / Functional studies showed that acetylcholine-induced relaxations in isolated aortas were impaired in a time-dependent manner, from the 4th-week to the 12th-week after ovariectomy. The impaired relaxations were partially restored by acute treatment with losartan [angiotensin II type 1 receptor (AT1R) blocker] and apocynin [NAD(P)H oxidase inhibitor]. The present results demonstrate that estrogen deficiency blunted endothelium-dependent relaxations due to impaired the NO bioavailability, which is closely associated with the reduced eNOS activity and elevated RAS expression and associated NAD(P)H oxidase-mediated oxidative stress in the vascular wall. / The present study shows that chronic consumption of cranberry juice restored the endothelium-dependent relaxations in aortas from ovariectomized rats. In ovariectomized rats, the phenylephrine-induced a higher active vascular tension; which was prevented by chronic consumption of cranberry juice. The present data also shows that cranberry juice administration significantly reduces the elevated serum levels of total cholesterol, triglyceride, high density lipoprotein (HDL) cholesterol, non-HDL (nHDL) cholesterol, and nHDL/HDL. The active ingredients in the cranberry juice organic extract accounting for the vascular benefit remain to be further examined even though the extract causes endothelial NO-dependent relaxations in normal rat aortas and contains several bioactive compounds, some of which may protect the vascular function. This study provides the first line of evidence concerning a significant vascular benefit of chronic consumption of cranberry juice during estrogen deficiency. (Abstract shortened by UMI.) / The present study used ovariectomized female rats that mimic the "equivalent" state of menopause in human and investigated whether dysregulation of RAS components contribute to endothelial dysfunction and whether chronic treatment with ACEI (enalapril) or ARB (valsartan) could restore endothelial function in ovariectomized rats. / The second objective of the present study was to investigate whether or not consumption of cranberry juice, a popular drink in Western countries, could restore endothelial function during estrogen deficiency and to elucidate the cellular mechanisms underlying the improved endothelial function. / Yung, Lai Ming. / Adviser: Huana Yu. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3252. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 148-168). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Many reptiles, including the red-eared slider turtle (Trachemys scripta elegans), exhibit temperature-dependent sex determination (TSD). Temperature determines sex during a temperature sensitive period (TSP), when gonadal sex is labile to both temperature and hormones -- particularly estrogen. Estrogen production is a key step in ovarian differentiation for many vertebrates, including TSD reptiles, and temperaturebased differences in aromatase expression during the TSP may be a critical step in ovarian determination. Steroidogenic factor-1 (Sf1) is a key gene in vertebrate sex determination and regulates steroidogenic enzymes, including aromatase. The biological actions of steroid hormones are mediated by their receptors, defined here as the classic transcriptional regulation of target genes. To elucidate the mechanism of estrogen action estrogen during sex determination, I examined aromatase, Sf1, ER[alpha], ER[beta], and AR expression in slider turtle gonads before, during and after the TSP, as well as following sex reversal via temperature or steroid hormone manipulation by administering exogenous estradiol (E2) or aromatase inhibitor (AI) to the eggshell. Sf1 is expressed at higher levels during testis development and following maleproducing temperature shift and AI treatment, while aromatase increases during ovary determination and feminizing temperature shift and E2 treatment. My results do not lend support to a role for Sf1 in the regulation of aromatase expression during slider turtle sex determination, but do support a critical role for estrogen in ovarian development. Estrogen receptor [alpha] and AR levels spike at the female-producing temperature just as aromatase levels are increasing during ovarian sex determination, while ER[beta] remains constant and only increases late in ovarian differentiation -- well after estrogen levels have increased, indicating that ER[alpha] and ER[beta] may have distinct roles in slider turtle ovarian development. Estrogen receptor [alpha] and ER[beta] are expressed along developing sex cords in the absence of estrogen (AI treatment). When shifted to female-producing temperatures, embryos maintain medullary ER[alpha] and AR expression while ER[beta] is reduced. By contrast, ER[alpha] and ER[beta] redirect to the cortex in E2-created ovaries. Warmer temperature and E2 result in the same endpoint (ovarian development), but may entail different steroid signaling patterns between temperature- and estrogen-induced feminization. / text