Thesis (Ph.D.)--University of Wollongong, 2005. / Typescript. Includes bibliographical references: leaf 279-310.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 171-225). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 171-225). Also available on the Internet.

Thesis (M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 107-127)

Preservation of giant pandas, Ailuropoda melanoleuca, is a worldwide concern. This study was designed to examine dietary and reproductive challenges associated with panda management. Phytoestrogens are natural plant compounds that mimic estrogen and often negatively impact mammalian reproduction. Phytoestrogens in bamboo, the panda’s primary food source, is unknown. Here, estrogen radioimmuno- and receptor-binding assays revealed estrogenic activity in three species of Phyllostachys bamboo. These results present indirect evidence of phytoestrogenic mimics in bamboo, but their relevance is still unknown. Studies were also conducted to observe panda reproductive behaviors in an attempt to augment the use of an artificial vagina (AV) for semen collection. A preliminary study confirmed the panda could differentiate between estrus urine and a water ‘control.’ However, when estrus urine was placed on the AV as an attractant, the subject didn’t approach the AV. Further investigation of dietary challenges and reproductive alternatives are needed to substantiate these findings.

The fall in circulating oestrogen (E2) after the menopause leads to an increased rate of bone remodelling, excessive osteoclast activity and a greater fracture risk. Until recently hormone replacement therapy (HRT) was prescribed to post-menopausal women to prevent bone loss, however HRT is associated with an elevated incidence of cardiovascular disease, stroke and cancer. These side-effects led to an interest in naturally occurring compounds with oestrogenic action such as phytoestrogens (PEs), which are non-steroidal-plant derived compounds. Human trials and animal studies suggest a beneficial effect of PEs on bone mass, although their ability to modify osteoclast formation in response to key inflammatory cytokines has not been examined. The aim of the following studies was to determine the effect of physiologically relevant concentrations of genistein, coumestrol and daidzein on TNF-α-induced osteoclast formation, osteoblasts differentiation and T cell activity. Genistein (10-7 M), daidzein (10-5 M), and coumestrol (10-7 M) significantly reduced TNF-α-induced TRAP positive osteoclast formation and bone resorption, which was prevented by the E2 antagonist ICI 182,780. The suppressive action on osteoclast formation was associated with a significant reduction in TNF-α-induced c-fos and NFATc1 mRNA expression and NFATc1 nuclear translocation. Constitutive c-fos expression prevented the inhibitory action of PEs on osteoclast differentiation, resorption and NFATc1 expression. The effect of PEs, in the presence or absence of the anabolic nutritional factor zinc, on osteoblasts differentiation and bone nodule formation was examined in-vitro. Coumestrol (10-5 to 10-7 M), daidzein (10-5 to 10-6 M) and genistein (10-5 M) enhanced bone nodule formation and ALP activity in human osteoblasts, and this effect was significantly augmented in the presence of zinc (10-5 M). Furthermore, PEs and zinc increased Runx2 mRNA expression and Zn2+ augmented the inhibitory effect of PEs on RANKL/OPG ratio. This suggests that in addition to the direct inhibitory effect on osteoclast formation PEs also in-directly reduce the osteoblastsic stimulus for osteoclast formation and promote bone formation. E2 deficiency is thought to promote osteoclastogenesis by modifying Thelper1 (Th1) cell proliferation and inflammatory cytokine production in particular TNF-α. I therefore examined the effect of PEs on T cell proliferation and inflammatory cytokine production. All PEs prevented the augmentative effect of con A stimulated T cells on osteoclast formation in co-culture. However the mechanism of action varied, genistein reduced con A stimulated TNF-α, IL-1β and RANKL expression with little effect on viability, coumestrol decreased cell viability and TNF-α expression whereas the inhibitory effect of daidzein was mediated via suppression of viable T cell number. This study provides novel evidence that PEs have multiple effects on bone cell activity, directly inhibiting TNF-α-induced osteoclast formation, reducing the osteoblasts and T cell derived stimulus for osteoclast formation and augmenting osteoblasts differentiation and bone formation. Thus, PEs have a potential role in the treatment of post-menopausal osteoporosis and inflammatory skeletal disorders and that the beneficial effect noted in previous studies is mediated through multiple mechanisms.

Le cancer du sein reste la principale cause de décès par cancer chez les femmes et est connu pour la divergence des comportements cliniques et des résultats pour les patientes, malgré les caractéristiques histopathologiques courantes au moment du diagnostic. Cela s'explique par la grande hétérogénéité histologique et moléculaire de la maladie, qui rend difficile le choix d'une thérapie adaptée à chaque patient.L'épigénétique se rapporte aux modifications du phénotype et de l'expression génique. Les modifications épigénétiques du génome peuvent être acquises de novo et sont potentiellement héritées. Les mécanismes épigénétiques agissent pour modifier l'accessibilité de la chromatine à la régulation de la transcription localement et globalement via des modifications de l'ADN et par des modifications ou des réarrangements de nucléosomes. L'épigénétique consiste en plusieurs mécanismes moléculaires: modifications de l'histone, petits ARN non codants ou anti-sens et méthylation de l'ADN étroitement interconnectés.L'incidence et la mortalité par cancer du sein sont plus élevées (incidence environ trois fois supérieure) dans le monde occidental que dans les pays d'Asie avec des différences régionales dans les pays occidentaux. Plusieurs études impliquant des immigrés des pays occidentaux suggèrent que le mode de vie et l'alimentation sont deux des causes principales de ces différences. Un apport alimentaire élevé en phytoestrogènes, principalement sous forme de produits à base de soja, peut produire des taux circulants de phytoestrogènes à effets œstrogéniques. Des études épidémiologiques et expérimentales suggèrent qu'un régime alimentaire riche en phytoestrogènes pouvait avoir des effets protecteurs contre sur les affections liées aux œstrogènes, telles que le cancer du sein.Sur la base de ces informations, nous avons étudié les effets du traitement par les phytoestrogènes; génistéine, daidzéine et 17-β-estradiol sur la modification post-traductionnelle des histones, telles que la méthylation de la lysine et l’acétylation des histones H3 et H4 dans des lignées cellulaires du cancer du sein. Nous avons ensuite étudié les effets de l'inhibiteur de la méthylation de l'histone et de l'inhibiteur de l'histone désacétylase sur la triméthylation et l'acétylation de l'histone-lysine dans les lignées cellulaires du cancer du sein. Nous avons utilisé deux lignées cellulaires de cancer du sein, MCF-7 et MDA-MB-231, chacune traitée respectivement avec de l'hydrochlorure de 3-désazanule (DZNep) [5 µM] (HMTi), du butyrate de sodium (NaBu) [2 mM] (HDACi) et de l'acide de type Suberoylanilide Hydroxamic (SAHA) [1 µM] (HDACi). Enfin, nous avons mené des études sur toutes les lignées cellulaires atteintes de tumeurs du sein afin d'évaluer l'immunoprécipitation de la chromatine (PIP) de certaines modifications de l'histone dans le cancer. Les niveaux relatifs de trois histones modifiées, y compris H3K27me3 (histone 3 Lysine 27 méthylation), H3K9ac (Histone 3 Lysine 9 acétylation) et H3K4ac (Histone 3 Lysine 4 acétylation) seront déterminés dans les tumeurs du sein par rapport au tissu normal correspondant selon le classement de Saint-Gall. Aujourd'hui, ChIP a été couplé à des puces à ADN de promoteur afin d'évaluer les mécanismes de régulation du gène humain à l'échelle du génome. La technologie de la puce sur puce pourrait être utilisée pour étudier les altérations de l'expression globale des gènes dans la tumorigenèse. Ici, nous avons étudié les gènes exprimés de manière différentielle associés aux histones modifiées H3K27me3, H3K9ac et H3K4ac dans les tumeurs du sein à l'aide de microréseaux Agilent SurePrint G3 400kX2 contenant environ 21 000 transcrits humains. Nous analyserons les régions enrichies de chaque promoteur de gène dans trente tumeurs du sein par rapport à des échantillons de tissus normaux. Les échantillons de tumeurs du sein seront classés en fonction de leur profil clinique, en particulier du statut des récepteurs hormonaux. / Breast cancer remains the leading cause of cancer-related deaths in women, and is noted for conflicting clinical behaviors and patient outcomes, despite common histopathological features at diagnosis. This can be explained by the high histological and molecular heterogeneity of the disease, making it hard to choose a therapy adapted uniquely to each patient. Epigenetics refer to changes in phenotype and gene expression. Epigenetic modifications of the genome can be acquired de novo and are potentially inherited. Epigenetic mechanisms work to change the accessibility of chromatin to transcriptional regulation locally and globally via modifications of the DNA and by modifications or rearrangements of nucleosomes. Epigenetics consist in several molecular mechanisms: histone modifications, small non-coding or antisense RNAs and DNA methylation that are closely interconnected. The incidence and mortality of breast cancer is high in the Western world as compared with countries in Asia. There are also differences in the regional cancer incidence rates in Western countries. Several studies involving immigrants to Western countries suggest that lifestyle and diet are two of the main causes of these differences. In Eastern countries, the incidence of breast cancer is approximately one-third that of Western countries, whilst their high dietary intake of phytoestrogens, mainly in the form of soy products, can produce circulating levels of phytoestrogens that are known experimentally to have estrogenic effects. An increasing number of epidemiological and experimental studies have suggested that the consumption of a 4 phytoestrogen-rich diet may have protective effects on estrogen-related conditions, such as breast cancer.Based upon this information, we studied the effects of treatment phytoestrogens; genistein, daidzein and 17-β-estradiol on the post-translational modification of histones such as lysine methylation and acetylation of histones H3 and H4 in breast cancer cell lines. Subsequently, we studied the effects of histone methylation inhibitor and histone deacetylase inhibitor on histone lysine trimethylation and acetylation in breast cancer cell lines. For this study, we used two breast cancer cell lines MCF-7 and MDA-MB-231. Each cell line was treated respectively with 3-Deazaneplanocin A hydrochloride (DZNep) [5 μM] (HMTi), Sodium Butyrate (NaBu) [2 mM] (HDACi) and Suberoylanilide Hydroxamic acid (SAHA) [1 μM] (HDACi) for 48 hours. Finally, we completed studies in all cell lines with breast tumors to assess Chromatin ImmunoPrecipitation (ChIP) of selected histone modifications in cancer. The relative levels of three modified histones, including H3K27me3 (Histone 3 Lysine 27 Methylation), H3K9ac (Histone 3 Lysine 9 Acetylation), and H3K4ac (Histone 3 Lysine 4 Acetylation) will be determined in breast tumors compared to matched normal tissue according to the classification of Saint Gallen. Today, ChIP has been coupled with promoter DNA microarrays to evaluate the mechanisms of human gene regulation on a genome-wide scale. ChIP-on-chip technology could be used to investigate the alterations of global gene expression in tumorigenesis. Here, we investigated differentially expressed genes associated with modified histones H3K27me3, H3K9ac and H3K4ac in breast tumors by Agilent SurePrint G3 400kX2 microarrays containing approximately 21,000 of human transcripts. We will scan the enriched regions at each gene promoter in thirty breast tumors compared with normal tissue samples. Breast tumor samples will be classified according to their clinical profiles, especially hormone receptor status.

Phytoestrogens are plant-derived compounds with oestrogenic activity. They are common in both human and animal diets, particularly through soy-based foods. This study assessed whether the reproductive function of male rats is affected by exposure to a high phytoestrogen diet during adulthood and examined possible mechanisms through which phytoestrogens may disrupt reproductive function. Experiments focused on the epididymis, a steroid-regulated organ responsible for the maturation, transport, and storage of sperm. Adult male rats, bred and raised on a low phytoestrogen diet, were either transferred to a high phytoestrogen diet (experimental), or remained on the low phytoestrogen diet (control). Litter size is a measure of fecundity and after 3 days on the high phytoestrogen diet litter size was reduced. This effect on fecundity was transient as litter sizes returned to control levels by day 12. The reduced fecundity at day 3 could not be explained by changes in sperm concentration. Plasma gonadotrophin levels and testicular testosterone levels were not affected by phytoestrogen exposure, however, the expression of steroid hormone receptors in the epididymis was affected, coincidental with reduced fecundity. The gene expression of oestrogen receptor alpha and androgen receptor was increased in the initial segment of the epididymis and decreased in the cauda epididymis. Additionally, lipid peroxidation of epididymal sperm was significantly increased in rats fed the high phytoestrogen diet for 3 days. It is concluded that acute exposure to the high phytoestrogen diet disrupts the steroid regulation of the epididymis, disrupting its normal function. This results in decreased sperm quality, thereby reducing fecundity.

Thesis (Ph. D.)--University of Massachusetts Amherst, 2009. / On title page, the 'a' in ERa is symbolized by the Greek symbol for alpha. Includes bibliographical references (p. 108-124). Print copy also available.

Thesis (M.Phil.) - University of St Andrews, March 2007.