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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

Antibacterial activity of liposome encapsulated cyclo(TYR-PRO)

Tshanga, Siphokazi Sisanda January 2011 (has links)
Cyclic dipeptides (CDPs) are amino acid-based compounds, some of which possess antibacterial activity. The encapsulation of certain drugs into liposomes has been found to improve their activity in terms of bioavailability and duration of action. Liposomes are small vesicles that are under investigation as drug carriers for the delivery of therapeutic agents. A number of liposome formulations are currently under clinical trial review, whilst some have already been approved for clinical use. The aim of this study was to optimize a liposomal cyclo(Tyr-Pro) formulation and to assess its antibacterial activity against various Gram-positive and Gram-negative bacteria. Response surface methodology (RSM) using the central composite design (CCD) model was used to optimize liposomal formulations of cyclo(Tyr-Pro) for each of the four bacteria, namely Bacillus cereus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Percent drug encapsulated and bacterial inhibition were investigated with respect to two independent variables, i.e. lipid composition and cholesterol content. Design Expert 8 was used for the purpose of finding the combination of independent variables that would yield an optimal formulation for each bacterium. The model selected by the software failed to adequately correlate the predicted models to the experimental data. The in vitro experiments showed that the antibacterial activity of liposome-encapsulated cyclo(Tyr-Pro) was superior to that of its free counterpart. Binding maximum or Bmax for the encapsulated compound at concentrations as low as 0.412 mg/ml, was significantly higher than that obtained for free cyclo(Tyr-Pro) which was tested at a concentration of 20 mg/ml. Furthermore, encapsulation of cyclo(Tyr-Pro) into a liposome formulation enhanced its potency. This was evident in the lower IC50 values for the liposomal compound when compared to free cyclo(Tyr-Pro).
2

A homoeopathic drug proving of ivory from the male African elephant (Loxodonta africana) with a subsequent comparison to Lac Loxodonta africana

Forbes, Barry January 2008 (has links)
Thesis (M.Tech.: Homoeopathy)--Durban University of Technology, 2008 / Introduction This dissertation entails a homoeopathic proving of ivory from the male African elephant (Loxodonta africana) 30CH with a subsequent comparison to Lac Loxodonta africana. Objectives The primary objective of this proving was to determine the effects of homoeopathically prepared ivory from the male African elephant (Loxodonta africana) in a 30CH dilution and was achieved by administering the remedy to a group of healthy individuals (provers) who will document all symptoms that arise as a result of taking the remedy. These symptoms will be used to identify the therapeutic indications of homoeopathic ivory. With these specific indications being documented the remedy can then be utilized in the sick individual, that present with similar symptoms, to induce a cure. A further objective of this proving is to report any variation that may exist in the comparison of two remedies, namely Lac Loxodonta africana (milk derived from the African elephant) and the remedy used in this proving, ivory from the male African elephant (Loxodonta africana). Methodology The substance was triturated up until the 3CH and subsequently converted into a liquid potency to be potentised up until the 30CH. Granules were then impregnated with the 30CH liquid potency. Ten impregnated granules were then placed in each individual ii lactose powder sachets. A total of six powders were dispensed to the proving participants. The proving was conducted as a double blind placebo controlled study with a total of twenty-six (26) provers that met the inclusion criteria (Appendix A). The group was made up of both homoeopathic students as well as the general public of varying ages, race and gender. The total group was randomly divided into two groups, twenty (20) of which received the homoeopathic remedy, the remainder (6) received placebo. A full case history of each prover was taken before commencing the proving as well as on completion of the study. Each individual prover kept a journal, starting a week before the proving, which was continued while taking the remedy and ceased when all symptoms had abated. Once all provers had completed the proving, the information received from the provers through the journals from both groups was collated, assessed and analyzed. A comparison was then made between this proving and Lac Loxodonta africana to assess whether any similarities or differences were evident. The comparison was made on symptom similarities and rubric analysis. Results The proving of ivory from the African elephant (Loxodonta africana) revealed a variety of symptoms. A total of 32 systems were affected in the twenty provers who received the remedy. 716 symptoms were recorded, 83 of which were new symptoms. The systems that were predominately affected were the mind, head and extremities. Many symptoms were confirmed to be similar to those identified in the proving of Lac Loxodonta africana, though differences were also acknowledged.
3

A homoeopathic drug proving of ivory from the male African elephant (Loxodonta africana) with a subsequent comparison to Lac Loxodonta africana

Forbes, Barry January 2008 (has links)
Thesis (M.Tech.: Homoeopathy)--Durban University of Technology, 2008 / Introduction This dissertation entails a homoeopathic proving of ivory from the male African elephant (Loxodonta africana) 30CH with a subsequent comparison to Lac Loxodonta africana. Objectives The primary objective of this proving was to determine the effects of homoeopathically prepared ivory from the male African elephant (Loxodonta africana) in a 30CH dilution and was achieved by administering the remedy to a group of healthy individuals (provers) who will document all symptoms that arise as a result of taking the remedy. These symptoms will be used to identify the therapeutic indications of homoeopathic ivory. With these specific indications being documented the remedy can then be utilized in the sick individual, that present with similar symptoms, to induce a cure. A further objective of this proving is to report any variation that may exist in the comparison of two remedies, namely Lac Loxodonta africana (milk derived from the African elephant) and the remedy used in this proving, ivory from the male African elephant (Loxodonta africana). Methodology The substance was triturated up until the 3CH and subsequently converted into a liquid potency to be potentised up until the 30CH. Granules were then impregnated with the 30CH liquid potency. Ten impregnated granules were then placed in each individual ii lactose powder sachets. A total of six powders were dispensed to the proving participants. The proving was conducted as a double blind placebo controlled study with a total of twenty-six (26) provers that met the inclusion criteria (Appendix A). The group was made up of both homoeopathic students as well as the general public of varying ages, race and gender. The total group was randomly divided into two groups, twenty (20) of which received the homoeopathic remedy, the remainder (6) received placebo. A full case history of each prover was taken before commencing the proving as well as on completion of the study. Each individual prover kept a journal, starting a week before the proving, which was continued while taking the remedy and ceased when all symptoms had abated. Once all provers had completed the proving, the information received from the provers through the journals from both groups was collated, assessed and analyzed. A comparison was then made between this proving and Lac Loxodonta africana to assess whether any similarities or differences were evident. The comparison was made on symptom similarities and rubric analysis. Results The proving of ivory from the African elephant (Loxodonta africana) revealed a variety of symptoms. A total of 32 systems were affected in the twenty provers who received the remedy. 716 symptoms were recorded, 83 of which were new symptoms. The systems that were predominately affected were the mind, head and extremities. Many symptoms were confirmed to be similar to those identified in the proving of Lac Loxodonta africana, though differences were also acknowledged. / M
4

A homoeopathic drug proving of the ivory of the male African elephant (Loxodonta africana) with a subsequent comparison to the doctrine of signatures

Speckmeier, Claire Tamryn January 2008 (has links)
Thesis (M.Tech.: Homoeopathy)-Durban University of Technology, 2008. xiv, 222 leaves / A proving of ivory from the male African elephant (Loxodonta africana) 30CH was conducted. The proving symptoms were then analysed according to the doctrine of signatures, and compared to the proving symptoms of Lac Loxodonta africana. Aims and Objectives of the study The aim of this study was to identify the effects of ivory from male African elephant (Loxodonta africana) in a 30CH dilution, on healthy provers, and to record the clearly observable signs and symptoms produced by the provers, so as to determine the material medica of the proven substance. The objective of the study was to analyze the symptoms obtained from the proving according to the doctrine of signatures, and to establish any correlation that may exist between the homoeopathic drug picture produced and this doctrine. Methodology The remedy was derived from the tusk of a male african elephant (Loxodonta africana) and was prepared in accordance to the German Homeopathic Pharmacopoeia (Drishien, 2003:36-38). The remedy was dispensed in the form of six lactose powders. The research was conducted as a randomised, double blind placebo controlled study. A group of provers (26) that were carefully selected from the general public (Appendix A) were divided into two groups. Recruitment commenced by obtaining suitable provers through speaking to fellow homoeopathic students, as ii well as members of the general public. The researchers conducted interviews with potential provers, excluding those that did not meet the inclusion criteria (Appendix A). The provers were randomly divided into two groups, and instructed to begin recording in their journals a week before starting the remedy, and a week after taking the remedy. The provers continued to record all symptoms until the symptoms abated and continued recording after this time for another two weeks. Once the proving had been completed another full case history and physical exam was performed. Results After the results were collaborated the proving symptoms were then analysed according to the doctrine of signatures. The results of this proving indicated that Loxodonta africana has the potential to be a valuable remedy in homoeopathic practice. Proving signs and symptoms revealed that the remedy could be indicated for mental and emotional conditions as well as a variety of physical diseases. The results of this research confirmed the hypothesis that the proving of Loxodonta africana 30CH would produce clear observable signs and symptoms when administered to healthy individuals. The results of this research also confirmed the second hypothesis that a comparison would exist between the proving symptoms and a doctrine of signatures analysis. Conclusion Thus the proving of Loxodonta africana and the subsequent comparison to the doctrine of signatures has the potential to become a well utilised homoeopathic remedy.
5

A homoeopathic drug proving of the ivory of the male African elephant (Loxodonta africana) with a subsequent comparison to the doctrine of signatures

Speckmeier, Claire Tamryn January 2008 (has links)
Thesis (M.Tech.: Homoeopathy)-Durban University of Technology, 2008. xiv, 222 leaves / A proving of ivory from the male African elephant (Loxodonta africana) 30CH was conducted. The proving symptoms were then analysed according to the doctrine of signatures, and compared to the proving symptoms of Lac Loxodonta africana. Aims and Objectives of the study The aim of this study was to identify the effects of ivory from male African elephant (Loxodonta africana) in a 30CH dilution, on healthy provers, and to record the clearly observable signs and symptoms produced by the provers, so as to determine the material medica of the proven substance. The objective of the study was to analyze the symptoms obtained from the proving according to the doctrine of signatures, and to establish any correlation that may exist between the homoeopathic drug picture produced and this doctrine. Methodology The remedy was derived from the tusk of a male african elephant (Loxodonta africana) and was prepared in accordance to the German Homeopathic Pharmacopoeia (Drishien, 2003:36-38). The remedy was dispensed in the form of six lactose powders. The research was conducted as a randomised, double blind placebo controlled study. A group of provers (26) that were carefully selected from the general public (Appendix A) were divided into two groups. Recruitment commenced by obtaining suitable provers through speaking to fellow homoeopathic students, as ii well as members of the general public. The researchers conducted interviews with potential provers, excluding those that did not meet the inclusion criteria (Appendix A). The provers were randomly divided into two groups, and instructed to begin recording in their journals a week before starting the remedy, and a week after taking the remedy. The provers continued to record all symptoms until the symptoms abated and continued recording after this time for another two weeks. Once the proving had been completed another full case history and physical exam was performed. Results After the results were collaborated the proving symptoms were then analysed according to the doctrine of signatures. The results of this proving indicated that Loxodonta africana has the potential to be a valuable remedy in homoeopathic practice. Proving signs and symptoms revealed that the remedy could be indicated for mental and emotional conditions as well as a variety of physical diseases. The results of this research confirmed the hypothesis that the proving of Loxodonta africana 30CH would produce clear observable signs and symptoms when administered to healthy individuals. The results of this research also confirmed the second hypothesis that a comparison would exist between the proving symptoms and a doctrine of signatures analysis. Conclusion Thus the proving of Loxodonta africana and the subsequent comparison to the doctrine of signatures has the potential to become a well utilised homoeopathic remedy.
6

Testing Guidelines for New Product Development

Egbert, Derek W. 04 June 2010 (has links) (PDF)
While many literary sources outline the product development process, few make mention of the prototyping and testing stage. This thesis suggests that because of its importance in the product development process, "Testing" should be documented as a major step and not just listed as a side note. As part of the testing step, it is suggested that standardized, in-use, and market tests be used to properly evaluate a product. While many rely solely on standardized tests to validate their products, effective in-use tests can be another vital tool that can prove the performance of the product in more specific and relevant applications. In-use tests are a major focus in this thesis and the process of developing and using these in-use tests is explored. A case study is used to prove that effective product development will follow the outlined testing procedure. Also, it shows that in-use testing, combined with other types of testing, can be a vital tool to ensuring the successful launch of a newly developed product. As a result of the case study, the traditional new product development process is amended and a set of guidelines are proposed for use in constructing a successful testing methodology for the new product development process.
7

The effects of long-term homocysteine-lowering treatment with folic acid, vitamin B6 and Vitamin B12 on vascular structure and function in stroke

Potter, Kathleen January 2009 (has links)
[Truncated abstract] An elevated total plasma homocysteine concentration (tHcy) is associated with an increased risk of myocardial infarction and ischemic stroke. Folic acid, vitamin B6 and B12 supplements significantly reduce tHcy even in people who are not overtly vitamin deficient. If homocysteine is a causal risk factor for atherothrombotic events, treatment with B-vitamins might prove a simple and cost-effective means to reduce cardiovascular risk. However, it remains unclear whether elevated tHcy causes atherosclerosis or is simply a risk marker. To prove that homocysteine is a modifiable risk factor for cardiovascular disease it is necessary to show that lowering tHcy reduces vascular risk. The aim of this study was to determine whether long-term homocysteine-lowering with B-vitamins would improve vascular structure and function in people with a history of stroke. This study was a cross-sectional sub-study of the Vitamins TO Prevent Stroke trial (VITATOPS), a multi-centre, randomised, double-blind, placebo-controlled clinical trial designed to test the efficacy and safety of B-vitamins (folic acid 2mg, vitamin B6 25mg and vitamin B12 0.5mg) in the prevention of vascular events in patients with a recent history of stroke or transient ischemic attack. 173 VITATOPS participants were recruited for the current study. Age, sex, stroke type, medications, cardiovascular risk factors and smoking history were recorded and blood pressure, height, weight, waist and hip girth were measured in all subjects at least two years after randomisation. ... After a mean treatment period of 3.9 ± 0.9 years, the subjects randomised to vitamin treatment had significantly lower tHcy than the subjects randomised to placebo (7.9mol/L, 95%CI 7.5, 8.4 versus 11.8mol/L, 95%CI 10.9, 12.8; p<0.001). There were no significant differences between groups in CIMT (0.84 ± 0.17mm vitamins versus 0.83 ± 0.18mm placebo; p=0.74) or FMD (median of 4.0%, IQR 0.9, 7.2, vitamins versus 3.0%, IQR 0.6, 6.6 placebo; p=0.48). Pooled estimates from the meta-analyses showed that B-vitamin treatment reduces CIMT by 0.10mm (95%CI –0.20, -0.01mm) and increases FMD by 1.4%, (95%CI 0.7, 2.2), although these estimates may have been influenced by positive publication bias. The improvement in FMD was significant in studies of less than eight weeks duration but not in studies with longer treatment periods. The association between tHcy and CIMT and FMD was eliminated by adjustment for renal function and long-term B-vitamin treatment did not alter the strong linear relationship between tHcy and cystatin C. Lowering tHcy did not alter arterial wall inflammation assessed by 18FDG-PET, although small subject numbers meant we were unable to exclude a minor treatment effect. Long-term homocysteine-lowering with B-vitamin treatment did not improve CIMT or FMD or reduce arterial wall inflammation in people with a history of stroke. The relationship between tHcy and these markers of vascular risk was eliminated by adjustment for renal function. Our data are consistent with the hypothesis that elevated tHcy is a risk marker for cardiovascular disease rather than a modifiable causal risk factor.
8

Indole-3-carbinol in the maternal diet provides chemoprotection for the fetus against transplacental carcinogenesis by dibenzo[a,l]pyrene in the B6 129 mouse model : role of the Aryl Hydrocarbon Receptor

Yu, Zhen 30 November 2005 (has links)
Lymphomas and leukemias are the most common cancer in children and young adults and in utero exposure to carcinogens may contribute to the etiology of these cancers. A polycyclic aromatic hydrocarbon (PAH), dibenzo[a,l]pyrene (DBP), was administered to pregnant mice (15 mg/Kg b.w., gavage) on gestation day 17. Significant mortalities in young offspring were observed due to T-cell lymphoma. Lung and liver tumors also were observed in survivors at 10 months of age. To assess the role of the Aryl Hydrocarbon Receptor (AHR), we utilized crosses of B6129SF1/J (responsive) mice with strain 129S1/SvImJ (non-responsive). Offspring born to AHR non-responsive mothers had greater susceptibility to lymphoma, irrespective of offspring genotype. Responsive offspring displayed increased mortality if the mother was responsive. Lung adenomas showed Ki-ras mutations and exhibited a 50% decrease and a 35-fold increase in expression of Rb and p19/ARF mRNA, respectively. To examine the risk/benefit of maternal dietary phytochemical treatment against transplacental cancer, 2000 ppm indole-3-carbinol (I3C) was given to pregnant mice through diet from gestation day 9 till weaning. I3C significantly lowered mortality caused by lymphomas regardless of the maternal genotype, and also reduced lung tumor multiplicity in offspring born to AHR [superscript b-l/d] dams. Distribution of I3C in most maternal and fetal tissues was quantified following a single gavage of [¹⁴C]-I3C to the pregnant mice. DBP-DNA adducts were observed in both maternal and fetal tissues by ³³P postlabeling and HPLC analysis and were modulated by I3C and AHR genotype. I3C also modulated phase I and phase II enzyme protein expression in dams and gene expression in newborn thymus. I3C chemoprotection may involve modification of the bioavailability of DBP to the fetus and/or modulation of gene expression in the fetus as well. This is the first demonstration that transplacental exposure to an environmental PAH can induce a highly aggressive lymphoma in mice. These results raise the possibility that PAH exposures to pregnant women could contribute to similar cancers in children and young adults and, that the addition of chemoprotective agents to the maternal diet may reduce cancer risk among offspring. / Graduation date: 2006
9

Effect of dietary fluoride on selenite toxicity in the rat

Yu, Qing, 1966- 28 January 1992 (has links)
Two factorial experiments were conducted to determine if high dietary fluoride would inhibit selenite toxicity in rats. In each study, two levels of selenite (0.05 and 5 mg/kg diet) were matched against two levels of fluoride (1 and 150 mg/kg diet) for either 6 or 8 weeks. Fluoride failed to prevent the depressive effect of selenite on food intake and body weight gain in either study. Although liver selenium concentration was slightly (15%) but significantly (P < 0.005) reduced when the highest fluoride and selenium level were combined in the first study, this effect could not be repeated. These three measures therefore failed to provide evidence for a fluoride and selenium interaction. Fluoride, however, prevented hepatic necrosis seen in most of the selenite-toxic rats. Hepatic lesions seen histologically in selenite-toxic rats were not observed for either kidney or heart. With regard to a possible mechanism for the fluoride effect upon selenite liver pathology, fluoride partially (26%) but significantly (P < 0.025) reduced thiobarbituricreactive substances (an indicator of peroxidative cell membrane damage) in selenite-toxic rats, but there was no fluoride effect on an enzyme system (liver xanthine oxidase) that potentially could generate an initiator of lipid peroxidation. In agreement with results of others, fluoride deposition into bone was inconsistently affected by selenite, Overall, the protective effect of fluoride on selenite toxicity appears to be confined to liver pathology. The exact mechanism for this effect, however, remains unclear. / Graduation date: 1992
10

Development and testing of liposome encapsulated cyclic dipeptides

Kilian, Gareth January 2011 (has links)
Cyclic dipeptides have been well characterized for their multitude of biological activities, including antimicrobial and anticancer activities. Cyclo(His-Gly) and cyclo(His-Ala) have also recently been shown to possess significant anticancer activity against a range of cell lines, despite the limitations of these two molecules with respect to their physicochemical properties. Low Log P results in poor cell permeability which can often be problematic for drugs with intracellular mechanisms of action. It can also results in poor biodistribution, and theoretical Log P values for cyclo(His-Gly) and cyclo(His-Ala) were extremely low making them ideal candidates for inclusion into a nanoparticulate drug delivery system. The aim of this study was therefore to formulate and evaluate liposome-encapsulated cyclic dipeptides that increase the tumour-suppressive actions of the cyclic dipeptides, while showing a high degree of specificity for tumour cells. While liposomes are relatively simple to prepare, inter batch variation, low encapsulation and poor stability are often problematic in their production and this has lead to very few liposomal products on the market. This study aimed at using a comprehensive statistical methodology in optimizing liposome formulations encapsulating cyclo(His-Gly) and cyclo(His-Ala). Initial screening of potential factors was conducted using a 25-1 fractional factorial design. This design made use of two levels for each of the five factors and abbreviated the design to minimize runs. Although not much information is provided by these types of designs, the design was sufficient in identifying two critical factors that would be studies further in a more robust design. The two factors selected, based on the screening study, were cholesterol and stearylamine content. These two factors were then used in designing a response surface methodology (RSM) design making use of a central composite rotatable vii design (CCRD) at five levels (-1.5, -1, 0, 1, 1.5) for each factor in order to better understand the design space. Various factors influenced the measured responses of encapsulation efficiency, zeta potential, polydispersity index, cellular uptake and leakage, but most notable were the adverse effects of increasing stearylamine levels on encapsulations efficiency and cholesterol levels on leakage for both cyclo(His-Gly) and cyclo(His-Ala) liposomes. Optimized formulations were derived from the data and prepared. Fair correlation between the predicted and measured responses was obtained. The cytotoxic activity of the encapsulated cyclic dipeptides were assessed against HeLa and MCF-7 cells and found to have limited improvement in activity. However, modification of the polyethylene glycol (PEG) grafted to the liposome surface in order to target folate receptors showed good benefit in significantly decreasing the IC50 values recorded in all cells lines tested, particularly low folate HeLa cells with the lowest IC50 being recorded as 0.0962 mM for folate targeted cyclo(His-Ala). The results therefore indicate that hydrophilic cyclic dipeptides are ideal candidates for inclusion into targeted drug delivery systems such as liposomes. Key words: Liposomes, cyclo(His-Gly), cyclo(His-Ala), cyclic dipeptides, HeLa, MCF-7, folate receptors, factorial design, response surface methodology (RSM), central composite rotatable design (CCRD).

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