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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

Preparation, stability and in vitro evaluation of liposomes containing amodiaquine / Jacques C. Scholtz

Scholtz, Jacques Coenraad January 2010 (has links)
Malaria is a curable disease that claims nearly one million lives each year. Problems with the treatment of malaria arise as resistance spreads and new treatment options are becoming less effective. The need for new treatments are of the utmost importance. Liposomes combined with antimalarials are a new avenue for research as liposomes can increase the efficacy of drugs against pathogens, as well as decreasing toxicity. Amodiaquine is a drug with known toxicity issues, but has proven to be effective and is, therefore, a prime candidate to be incorporated into the liposomal drug delivery system. The aim of this study was to prepare, characterize and evaluate the toxicity of the liposomes with incorporated amodiaquine. The solubility of amodiaquine was determined and liposomes formulated with, and without, amodiaquine entrapped. Accelerated stability studies (at 5 'C, 25 'C with relative humidity of 60% and 40 'C with a relative humidity of 40%) were conducted during which the size, pH, morphology and the entrapment efficacy was determined. The toxicity was determined in vitro by analysing the levels of reactive oxidative species and lipid peroxidation caused by the formulations to erythrocytes infected with P. falciparum as well as uninfected erythrocytes with flow cytometry. The solubility study of amodiaquine in different pH buffers showed that amodiaquine was more soluble at lower pH values. Solubility in solution with pH 4.5 was 36.3359 ± 0.7904mg/ml when compared to the solubility at pH 6.8, which was 15.6052 ± 1.1126 mg/ml. A buffer with a pH of 6 was used to ensure adequate solubility and acceptable compatibility with cells. Liposomes with incorporated amodiaquine were formulated with entrapment efficacies starting at 29.038 ± 2.599% and increasing to 51.914 ± 1.683%. The accelerated stability studies showed the median sizes and span values remained constant for both liposome and amodiaquine incorporated liposomes at 5 'C. The higher temperatures, i.e. 25 'C and 40 'C, displayed increases in the median size, and decreases in the span for both formulations. The conclusion can, therefore, be made that both liposome and amodiaquine incorporated liposomes are stable at lower temperatures. The entrapment efficacy increased from initial values to nearly 100% during the course of the stability study. This was attributed to amodiaquine precipitating from the solution. The pH values of the liposomes and amodiaquine incorporated liposomes remained constant for each formulation; though the amodiaquine incorporated liposomes had a lower starting pH, the formulations are both thought to be stable in terms of the pH. Toxicity studies revealed low levels of reactive oxygen species as well as low levels of lipid peroxidation for both liposome and amodiaquine incorporated liposomes, on both erythrocyte and Plasmodium infected erythrocytes. From the toxicity studies it can be concluded that liposomes and amodiaquine incorporated liposomes are not toxic to erythrocytes and infected erythrocytes. It was concluded that liposomes incorporating amodiaquine could possibly be used as a treatment option for malaria. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2011.
22

Index and stability in bimatrix games : a geometric-combinatorial approach /

Schemde, Arndt von. January 2005 (has links)
School of Economics and Political Science, Diss.--London, 2005. / Literaturverz. S. [143] - 145. The work originates from the author's PhD thesis at the London School of Economics and Political Science. (Preface).
23

Credit growth, asset prices and financial stability in South Africa :|ba policy perspective / Chris Booysen

Booysen, Chris January 2013 (has links)
The worldwide economic downturn and recession in the second half of 2008 were mainly the result of the crises that influenced the world‟s financial markets. After the financial crisis, the extended period of rapid credit growth that was driven by asset price increases, especially property prices, came to an end. This identified two problems central to the theme of this study. The first problem was illustrated through the recent crisis, which showed that problems in the financial sector have a potentially destabilising effect on the economy, to such an extent that they also affect the real economy. The second problem highlighted by the recent financial crisis pertains to the current macroeconomic framework, which indicates policy failure to detect and deal with financial sector instabilities. The objective of this study was to develop a framework in which the influence that rapidly growing credit and asset prices have on financial stability could be determined. Two distinct empirical models were estimated in order to reach the main objective of this study. The first model established the influence that asset prices and credit growth have on the real economy. It concluded that a long-run relationship exists between inflation, real GDP, credit extended to the private sector, house prices and share prices. A bi-directional relationship was found between house and share price, which indicates the interdependence of asset prices in SA. The transmission channels assume that credit is influenced by interest rates, but the results also found that interest rates are largely influenced by credit. The second model determined the influence of asset prices and credit on financial stability. A significant long-run relationship was found between financial stability, share and house prices, and between share prices, credit and financial stability. It was found that credit and share prices can be used to signal financial instability, and share prices can help to determine future credit extended to the private sector. In addition, the empirical analysis indicated that a credit market squeeze will be experienced after a decrease in financial stability. Lastly, credit extended will increase as a result of shock to house and share prices and financial stability will decrease when there is a shock to share and house prices. / MCom (Economics), North-West University, Potchefstroom Campus, 2013
24

Credit growth, asset prices and financial stability in South Africa :|ba policy perspective / Chris Booysen

Booysen, Chris January 2013 (has links)
The worldwide economic downturn and recession in the second half of 2008 were mainly the result of the crises that influenced the world‟s financial markets. After the financial crisis, the extended period of rapid credit growth that was driven by asset price increases, especially property prices, came to an end. This identified two problems central to the theme of this study. The first problem was illustrated through the recent crisis, which showed that problems in the financial sector have a potentially destabilising effect on the economy, to such an extent that they also affect the real economy. The second problem highlighted by the recent financial crisis pertains to the current macroeconomic framework, which indicates policy failure to detect and deal with financial sector instabilities. The objective of this study was to develop a framework in which the influence that rapidly growing credit and asset prices have on financial stability could be determined. Two distinct empirical models were estimated in order to reach the main objective of this study. The first model established the influence that asset prices and credit growth have on the real economy. It concluded that a long-run relationship exists between inflation, real GDP, credit extended to the private sector, house prices and share prices. A bi-directional relationship was found between house and share price, which indicates the interdependence of asset prices in SA. The transmission channels assume that credit is influenced by interest rates, but the results also found that interest rates are largely influenced by credit. The second model determined the influence of asset prices and credit on financial stability. A significant long-run relationship was found between financial stability, share and house prices, and between share prices, credit and financial stability. It was found that credit and share prices can be used to signal financial instability, and share prices can help to determine future credit extended to the private sector. In addition, the empirical analysis indicated that a credit market squeeze will be experienced after a decrease in financial stability. Lastly, credit extended will increase as a result of shock to house and share prices and financial stability will decrease when there is a shock to share and house prices. / MCom (Economics), North-West University, Potchefstroom Campus, 2013

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