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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.
1

Studies on the Effects of Paraben Mixtures on MCF-7 Breast Cancer Cells in Culture

Webber, Kristie Elmslie January 2013 (has links)
Parabens are the esters of p-hydroxybenzoic acid and are commonly used as preservatives in personal care products, pharmaceutical preparations and cosmetics. Recently parabens have been found to be estrogenic, bringing into question if exposure to them is adversely affecting human health. Given exposure to multiple xenoestrogens is constant; research has been carried out to determine what effect combinations of xenoestrogens might have on human and environmental health. Parabens are almost always present in combinations in formulae as this increases their antimicrobial activity, so it is important to know what the effect of this is. The main aim of this study was to determine what the effect of combining methylparaben and butylparaben together has on the proliferation of MCF-7 breast cancer cells, which proliferate in the presence of estrogen. This study was carried out by exposing MCF-7 breast cancer cells to combinations of methylparaben and butylparaben and measuring cell proliferation by counting cells using a cytometer. The results show that butylparaben caused a greater increase in cell proliferation compared to methylparaben. When methylparaben and butylparaben were combined together, the resulting cell proliferation was greater than the cell proliferation produced by either methylparaben or butylparaben alone at a concentration twice the amount of either paraben concentration contained within the mixture. These results were analysed using Analysis of Variance, which determined the combination treatments were statistically different from the single treatments according to Fishers method. This suggests that there is a synergistic effect produced when methylparaben and butylparaben are combined together, however large variation and dose dependent discrepancies means this result is uncertain and further studies need to be carried out.
2

The qualitative and quantitative evaluation of estrogen and estrogen-mimicking substances in the South African water environment / Liesl van der Merwe

Van der Merwe, Liesl January 1998 (has links)
Recently some chemicals has been accused of mimicking the female hormone estrogen. The mode of action is termed estrogen-mimicking, because of the effects that is produced by these chemicals. Playing canary in a coal mine, wildlife was the first to indicate that something was wrong. Reproductive abnormalities such as abnormal sperm, reduced sperm production, cryptorchidism (undescended testes). abnormal hormone levels – particularly high estrogen ratios to that of testosterone. infertility, and genital abnormalities were all evidence that something in the environment was affecting the reproductive status of these animals. Also in humans instances like rising cases of infertility, abnormal sperm conditions and cases of breast cancer raised an increased concern about the potential disruptive effects of these substances on the human existence. After investigations were conducted, it was found that substances which enhance the quality of life like some detergents, agricultural products, additives to plastic, dyestuffs, paint components and pharmaceuticals to name but a few, all caused an abnormal reproductive status as seen in animals. The aims of this study were not to focus on the effect of these substances, but rather to identify estrogen and estrogen - mimics in the South African environment and to evaluate their presence in the water environment qualitatively and quantitatively with the most suitable analytical methods. Estrogen - mimics such as nonylphenol. o'p' and p'p' DDE, o'p' DDD, lindane, atrazine and the PCB's : Arochlor 1254 & Arochlor 1260 were found to contaminate the environment. The drinking water tested of the PWV area indicated that the water was free of these substances, and thus indicated a present safe situation. / Thesis (MSc (Farmaseutika))--PU for CHE, 1998
3

The qualitative and quantitative evaluation of estrogen and estrogen-mimicking substances in the South African water environment / Liesl van der Merwe

Van der Merwe, Liesl January 1998 (has links)
Recently some chemicals has been accused of mimicking the female hormone estrogen. The mode of action is termed estrogen-mimicking, because of the effects that is produced by these chemicals. Playing canary in a coal mine, wildlife was the first to indicate that something was wrong. Reproductive abnormalities such as abnormal sperm, reduced sperm production, cryptorchidism (undescended testes). abnormal hormone levels – particularly high estrogen ratios to that of testosterone. infertility, and genital abnormalities were all evidence that something in the environment was affecting the reproductive status of these animals. Also in humans instances like rising cases of infertility, abnormal sperm conditions and cases of breast cancer raised an increased concern about the potential disruptive effects of these substances on the human existence. After investigations were conducted, it was found that substances which enhance the quality of life like some detergents, agricultural products, additives to plastic, dyestuffs, paint components and pharmaceuticals to name but a few, all caused an abnormal reproductive status as seen in animals. The aims of this study were not to focus on the effect of these substances, but rather to identify estrogen and estrogen - mimics in the South African environment and to evaluate their presence in the water environment qualitatively and quantitatively with the most suitable analytical methods. Estrogen - mimics such as nonylphenol. o'p' and p'p' DDE, o'p' DDD, lindane, atrazine and the PCB's : Arochlor 1254 & Arochlor 1260 were found to contaminate the environment. The drinking water tested of the PWV area indicated that the water was free of these substances, and thus indicated a present safe situation. / Thesis (MSc (Farmaseutika))--PU for CHE, 1998
4

The qualitative and quantitative evaluation of estrogen and estrogen-mimicking substances in the South African water environment / Liesl van der Merwe

Van der Merwe, L. (Liesl) January 1998 (has links)
Thesis (MSc (Farmaseutika))--PU for CHE, 1998.

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