A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, March 2016. / Environmental temperature greatly affects many aspects of an ectotherm’s physiology. These effects can be so significant that temperature is often the foremost constraint determining an ectotherm’s distribution. However, establishing the link between these mechanistic limitations and distribution require often-intensive and costly investigations. In an attempt to improve efficiency and reduce cost, niche-based models are often implemented as a means to identify potential constraints. However, these approaches are mere hypotheses-generators, and do not directly establish causal links between geographic range and limiting factors. Furthermore, the mismatch of species-appropriate scale and resolution of input data are often not addressed in these models. This dissertation directly examined the relationship between a southern African skink, the Rainbow Skink (Trachylepis margaritifer) and environmental temperatures. It examined the effect of temperature on appetite, digestive efficiency, and gut transport times. It assessed the potential for this species to serve as a candidate for stress metabolite studies and evaluated how accurately a niche model predicted the environmental temperatures experienced at a fine-scale (i.e., speciesappropriate, microhabitat resolution) based on broad-scale temperature inputs. Additionally, the suitability of habitat quality proxies are assessed against both model predictions and on-the-ground measures made at a fine scale. Temperature significantly affected appetite, with low temperatures (25 °C) resulting in decreased appetite. Gut transit times are also significantly affected, but not in an expected pattern. At low temperatures (25 °C), gut transit time was decreased when compared to those recorded at an intermediate temperature (27 °C). Transit times however remained predictably low at high temperatures (32 °C). However, this unusual pattern in transit times had no effect on associated digestive efficiencies. Instead, digestive efficiencies remained equally high across these three temperatures tested. Additionally, habitat quality proxy measures in general aligned poorly to modeled predictions. No meaningful differences in habitat quality were found using typical thermal assessments of environmental means, but were when using skink-relevant and biologically meaningful ones. For T. margaritifer, continuous exposure to 22 °C impairs digestion and promotes skin lesions and eventual death under controlled conditions, and at sites where exposure to 22 °C were greatest, skinks appeared to be in the poorest condition, and many exhibited skin lesions. These findings strongly suggest that 22 °C may represent a lower thermal constraint for the species, and highlights the importance of mechanistic studies that directly investigate factors affecting a species’ physiological performance. In addition, techniques such as measuring glucocorticoids and their metabolites may better reflect habitat quality, as well as serving to validate selected habitat quality proxies. Overall, despite the everincreasing approaches available to conservationists and ecologists alike, this work emphasizes that if we are to take full advantage of these new techniques, in-depth, trait-specific mechanistic studies must maintain their place among them. / MT2016

MAGALHÃES JÚNIOR, G. A.; Síntese de Microesferas e Nanopartículas de Quitosana e Goma do Chichá (Sterculia striata) como Matriz para Liberação Controlada de Fármaco para Tratamento da Malária. 2012. 150 f. Tese (Doutorado em Química Orgânica) - Centro de Ciências, Universidade Federal do Ceará, 2012. / Submitted by José Jairo Viana de Sousa (jairo@ufc.br) on 2014-10-13T17:59:58Z No. of bitstreams: 1 2012_tese_gamjunior.pdf: 1352598 bytes, checksum: 6118587fb17b69a25b47e67cf693fd2e (MD5) / Approved for entry into archive by José Jairo Viana de Sousa(jairo@ufc.br) on 2014-11-11T23:10:43Z (GMT) No. of bitstreams: 1 2012_tese_gamjunior.pdf: 1352598 bytes, checksum: 6118587fb17b69a25b47e67cf693fd2e (MD5) / Made available in DSpace on 2014-11-11T23:10:43Z (GMT). No. of bitstreams: 1 2012_tese_gamjunior.pdf: 1352598 bytes, checksum: 6118587fb17b69a25b47e67cf693fd2e (MD5) Previous issue date: 2012 / The aim of this work was the synthesis and characterization of nano and microparticles for malaria drug delivery system. Chitosan microspheres of high molar mass (QTa) and chichá gum (CH) were synthesized by polyelectrolyte complexation and crosslinked with glutaraldehyde. The diameters of the microspheres crosslinked and non-crosslinked were 544  3 μm and 558  2 μm, respectively. The crosslinked beads were not soluble in acidic medium (pH 1.2). The swelling of microspheres was higher in pH 1.2 and that the crosslinked beads have less swelling than non-crosslinked. The sequential release of chloroquine from the microspheres was performed for 2 h followed by a release in pH 7.4. The crosslinked microsphere released 64% of chloroquine at pH 1.2, with a total of drug released of 92%. The release profile of the same sample at pH 7.4 provides a controlled release of the drug for about 50h. QT and CH nanoparticles were prepared using polyelectrolyte complexation and formation of Schiff base. In the formation of polyelectrolyte complex, parameters such as molecular weight of chitosan, the molar ratio of charge (n+/ n-), order of addition and concentration of the polyelectrolyte influence the size, zeta potential, polydispersity index and stability of the nanoparticles in solution. The zeta potential of particles in excess of QT was positive and when the charg molar ratio (n+/ n ) decreases to 0.1 the potential becomes negative due to the excess of CH. The nanoparticles diameters vary from 80 to 1,200 nm depending on the concentration of the polyelectrolyte and the chitosan used. Chitosan nanoparticles formed by a low molecular weight (QTb) were larger than those formed by chitosan of high molecular weight (QTa). The decrease of the charge ratio (n+/n-) and the polyelectrolyte concentrations lead to small size nanoparticle. The release of chloroquine in matrices of CH, QTa and QTb ratio ratio 5 and 0.1 lasted 15 days by releasing up to 99% of the drug, however only the ratio influenced the release profile. Nanoparticles formed by Schiff base reaction were produced. The influence of parameters such as degree of oxidation of CH, chitosan molar mass, addition and masses ration of polysaccharides on size, zeta potential and stability were investigated. The zeta-potential was positive for particles with an excess of QT and negative with excess CH. The particle diameters ranged from 30 to 450 nm, depending on the degree of oxidation of CH and the molar mass of QT. Particle formed with low oxidation of CH and high molar mass chitosan are bigger than those formed with low molar mass chitosan. A inverse behavior was observed when high oxidated CH was used. / Este trabalho tem como objetivo a síntese e caracterização de nano e micropartículas para liberação de fármaco para tratamento da malária. Microesferas de quitosana de alta massa molar (QTa) e goma do chichá (CH) foram sintetizadas por complexação polieletrolítica e reticuladas com glutaraldeído. Os diâmetros das microesferas reticuladas e não-reticuladas foram de 544  3 μm e 558  2 μm, respectivamente. As esferas reticuladas não foram solúveis em meio ácido (pH 1,2). Ensaios de intumescimento mostraram que as microesferas intumesciam mais em pH 1,2 do que em pH 7,4 e que as reticuladas possuíam menor intumescimento do que as não reticuladas. A liberação sequenciada de cloroquina, a partir das microesferas, foi realizada por 2 h em pH 1,2 seguida por uma liberação em pH 7,4. A microesfera reticulada liberou 64% da cloroquina em pH 1,2, com um total do fármaco liberado de 92%. O perfil de liberação da mesma amostra em pH 7,4 apresenta uma liberação controlada do fármaco por cerca de 50 h. Nanopartículas de QT e CH foram produzidas utilizando como rotas de síntese a complexação polieletrolítica e formação de base de Schiff. Na formação de complexos polieletrolíticos parâmetros como massa molar da quitosana, razão molar de carga (n+/n-), ordem de adição e concentração dos polieletrólitos influenciam no tamanho, potencial zeta, índice de polidispersividade e estabilidade das nanopartículas em solução. O potencial zeta das partículas com excesso de QT é positivo e quando se diminui a razão molar de carga (n+/n-) para 0,1 o potencial torna-se negativo devido o excesso de chichá. Os diâmetros das nanopartículas variaram de 80 a 1200 nm dependendo da concentração dos polieletrólitos e da quitosana utilizada. Nanopartículas formadas por quitosana de baixa massa molar (QTb) possuem tamanho maior do que as formadas por quitosana de alta massa molar (QTa). Quando a razão de cargas (n+/n-) e a concentração dos polieletrólitos diminuem o tamanho das nanopartículas também diminui. Na liberação da cloroquina em matrizes de CH, QTa e QTb de razão 5 e 0,1 duraram cerca 15 dias liberando até 99% do fármaco, porém apenas a razão de cargas influenciou no perfil da liberação. Nanopartículas formadas via base de Schiff foram preparadas. A influência de parâmetros tais como: grau de oxidação da goma do chichá, massa molar da quitosana, ordem de adição e razão entre as massas dos polissacarídeos foram investigados em relação ao tamanho, potencial zeta e estabilidade. O potencial zeta mostrou-se positivo para partículas com excesso de QT e negativo para partículas com excesso de CH. Os diâmetros das partículas variaram de 30 a 450 nm, dependendo do grau de oxidação do CH e da massa molar de QT. Para goma do chichá com menor grau de oxidação nanopartículas de QTa apresentaram-se maiores do que as formadas por QTb, e para a goma com maior grau de oxidação nanopartículas de QTb possuíam maiores tamanhos do que as formadas por QTa.

Thesis (Ph. D.)--Ohio University, 2005. / Title from PDF t.p. (viewed Jan. 26, 2007). Includes bibliographical references (p. 157-170).

Made available in DSpace on 2014-07-29T16:16:36Z (GMT). No. of bitstreams: 1 dissertacao aline silva.pdf: 641990 bytes, checksum: f01c5af83294c71fd63825142856d782 (MD5) Previous issue date: 2009-09-14 / Many species from Cerrado remain unknown in their biochemical characteristics and in their potential for food processing. This work had as objective to characterize the almond of chichá from the specie Sterculia striata A. St. Hill & Naudin, originated from Corrente (Piauí) in their biochemical components, analyze the changes in the chemical composition and the amounts of antinutritional factors after roasting. The almond of chicha presented high levels of protein, fiber, phosphorus, copper and manganese. The roasting held to 205°C for 11 minutes reduced the content of humidity from 6.0% to 2.1% and phytates from 10,6mg/g to 5.5 mg/g. There were no lectins, tannins, trypsin inhibitors and alpha-amylase was also a important result obtained. It was verified the absence of the enzymes polyphenol oxidase and peroxidase and a content of phenolics in the range of 107.7 mg/100g and 108.9 mg/100g in the raw and roasted almond respectively. The almond of chicha presented polyunsaturated fatty acids linoleic (3,8%) and linolenic acid (2,3%), high levels of monounsaturated (40%) and saturated (34.5%) and presence of fatty acids cyclopropenoid. Therefore, the almond chichá is rich in nutrients; however it is necessary to investigate the effects of eating cyclopropenoid in the concentration found in these almonds. This work reinforces the necessity of conservation and in deep studies of native plants from Cerrado / Muitas espécies do Cerrado ainda são pouco conhecidas, assim como suas características bioquímicas e seu potencial para processamento de alimentos. Este trabalho teve como objetivo caracterizar bioquimicamente a amêndoa de chichá da espécie Sterculia striata A. St. Hill & Naudin, oriunda de Corrente (Piauí) e verificar alterações na composição química e no teor de fatores antinutricionais após torrefação. A amêndoa de chichá mostrou-se ser um alimento com alto teor de proteínas, fibras, fósforo, cobre, zinco e manganês. A torrefação realizada a 205°C por 11 min resultou em perda de umidade de 6,0% para 2,1% e diminuição do fitato de 10,6 mg/g para 5,5 mg/g. A ausência de fatores antinutricionais como lectinas, taninos e inibidores de tripsina e alfa-amilase foi também um resultado importante. Verificou-se a ausência de peroxidase e polifenoloxidase e conteúdo de compostos fenólicos de 107,7 mg/100g e 108,9 mg/100g para amêndoas cruas e torradas, respectivamente. Por fim, têm-se ácidos graxos poliinsaturados linoléico (3,8%) e linolênico (2,3%), altos teores de monoinsaturados (40%) e saturados (34,5%) e presença de ácidos graxos ciclopropenoídicos. Assim, pode-se afirmar que a amêndoa de chichá é um alimento rico em nutrientes, mas é preciso investigar os efeitos da ingestão de ácidos ciclopropenoídicos na concentração encontrada. Este trabalho reforça a necessidade de conhecer e conservar as plantas nativas do Cerrado

In the research reported in this dissertation, the concept of classic conjugate imaging, a non-tomographic nuclear medicine technique, is modified such that activity of a radiopharmaceutical distribution in the striata can be estimated. A mathematical model is developed that extended the application of classic conjugate imaging to estimation of two distinct and aligned activity distributions. Error analysis of the mathematical model is performed to characterize the accuracy of the model and to benchmark the limitations of the model. Phantom experiments are performed to demonstrate the practical application of the model and to evaluate its accuracy. A Monte Carlo simulation model of conjugate imaging of activity uptake in the striata of a primate is developed to evaluate the accuracy of the modified conjugate imaging technique as applied in the use of a dedicate conjugate imaging system. In addition, the simulation model is used to determine and characterize the shielding design of the small field of view gamma cameras comprising the dedicated conjugate imaging system. The application of scatter correction is investigated to address the downscatter of high-energy photon emissions into the photopeak window and the inclusion of scattered primary photons in the photopeak window. In this dissertation, it is shown that the modified conjugate imaging technique developed can be used to estimate accurately activity uptake in each of two distinct and aligned activity distributions. The accuracy of the technique is shown to be comparable to that of clinical quantitative SPECT. The modified conjugate imaging technique used with the dedicated conjugate imaging system may, therefore, be a viable quantitative nuclear medicine technique for activity estimation of radiopharmaceutical uptake in the striata of Parkinsonian and schizophrenic patients. The portability and low cost relative to SPECT systems make a dedicated conjugate imaging system advantageous for clinics with Parkinsonian and schizophrenic patients, who are unable to travel due to physical or mental limitation.

No description available.

Although the interest in vegetable oils as feedstock for biofuel production is not a recent issue, this took great impetus by the need to have alternative energy sources to the use of oil and oil products, with a search for new sources of vegetable oil. The chichá (sterculia striata) is a large tree that measures 8-25 meters high, it is found in the Brazilian Atlantic Forest and it has fast growing, resistance to low temperatures and different altitudes. The seeds are cylindrical and flat with a black fur that comes off as dries. It has up to 42%almond oil, being a potential candidate for obtaining oil in Brazil. In recent years, many researches have been developed in order to make the production of biodiesel, by ethylic route, technically and economically viable. In this point, much has been done with respect to reactional aspects of this process. However, little researches have been done in order to solve problems related to separation and purification steps. Knowing the phase behavior of the systems is vital for the design, operation and control of these units. This study aimed to: 1) study the process of obtaining biodiesel from chichá oil, 2) perform experimental and theoretical study of the liquid-liquid equilibrium (LLE) involving representative substances of the phase equilibrium present in the chichá biodiesel production. It is expected that the experimental results obtained in this study may come to assist the industry of biodiesel production, providing biodiesel production data and phase equilibrium data to these ones. The results showed that the chichá has about 40% oil in its seed, the chichá biodiesel production reached 99% yield in esters using time ration of 0,5 hours, molar ratio oil/alcohol 1/10, 1,5 % oil mass in mass of catalyst and temperature of 30 °C. The data (LLE) for the ternary system chichá biodiesel + ethanol + glycerol and its tie-lines showed a very characteristic behavior, having no significant variation in studied temperatures. / Embora o interesse por óleos vegetais como matéria-prima para produção de bicombustíveis não seja um assunto recente, tomou grande impulso pela necessidade de se dispor de fontes de energia alternativas ao uso do petróleo e derivados, havendo uma busca por novas fontes de óleo vegetal. O chichá (Sterculia striata) é uma árvore de grande porte, de 8 a 25 metros de altura, encontrada na Mata Atlântica brasileira, com crescimento rápido, resistente a baixas temperaturas e diferentes altitudes. As sementes são cilíndricas e achatadas com uma pele preta que se desprende à medida que vai secando. Apresenta, na sua amêndoa até 42% de óleo, sendo uma candidata potencial para a obtenção de óleo no Brasil. Nos últimos anos, muitas pesquisas vêm sendo desenvolvidas visando tornar a produção de biodiesel, via rota etílica, técnica e economicamente viável. Neste sentido, muito têm sido realizado no tocante aos aspectos reacionais deste processo. Entretanto, pouco se tem pesquisado objetivando resolver os problemas relacionados às etapas de separação e purificação. Conhecer o comportamento de fases dos sistemas é vital para o projeto, operação e controle destas unidades. Este trabalho teve como objetivos: 1) estudar o processo de obtenção de biodiesel a partir do óleo de chichá; 2) realizar o estudo experimental e teórico do equilíbrio líquido-líquido (ELL) envolvendo substâncias representativas do equilíbrio de fases presentes na produção de biodiesel do chichá. Espera-se que os resultados experimentais obtidos neste trabalho possam vir a auxiliar o setor de produção de biodiesel, fornecendo a estes, dados de produção do biodiesel e dados do equilíbrio de fases. Os resultados encontrados mostraram que o chichá possui aproximadamente 40% de óleo em sua semente, a produção de biodiesel de chichá alcançou 99 % de rendimento em ésteres utilizando tempo de ração de 0,5 horas, razão molar óleo/álcool 1/10, 1,5% da massa do óleo em massa de catalisador e temperatura de 30 °C. Os dados do (ELL) para o sistema ternário biodiesel de chichá + etanol + glicerina e suas tie-lines mostraram um comportamento muito característico, não tendo variação significativa nas temperaturas estudadas.

Orientador: Paulo Sérgio Moreira Carvalho de Oliveira / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-17T09:19:12Z (GMT). No. of bitstreams: 1 Bottcher_Claudia_D.pdf: 2277526 bytes, checksum: fd9c885535eb1d45ead71daf14f43c8a (MD5) Previous issue date: 2010 / Resumo: A grande quantidade de frutos carnosos e a diversidade e abundância de formigas em ambientes tropicais faz com que a interação entre formigas e diásporos seja bastante comum. Atualmente sabe-se que estas interações envolvem dezenas de espécies de plantas e formigas em uma comunidade ecológica. Dentre as espécies da fauna de formigas que interagem com diásporos, Pachycondyla striata e Odontomachus chelifer destacam-se como dispersores de sementes caídas no solo e as características físicas e químicas de seus ninhos freqüentemente promovem o estabelecimento de plântulas. Contudo, apesar da reconhecida importância dessas formigas para algumas espécies de plantas, nada se sabe sobre a influência desses diásporos no desenvolvimento e reprodução de suas colônias. Com base nesse cenário, esta tese foi dividida em duas partes relacionadas. Na primeira parte, Capítulo I, investigamos as interações entre formigas e diásporos não-mirmecocóricos em três diferentes fisionomias florestais da Ilha do Cardoso (restinga, planície e encosta), sudeste do Brasil. Durante dois anos de amostras mensais 517 interações envolvendo 53 espécies de formigas e 48 espécies de diásporos foram observadas. A maior parte das interações ocorreu em floresta de planície (54.62%), e menos da metade ocorreu nas demais áreas, encosta (31.33%) e restinga (14.06%). Myrmicinae teve o maior número de espécies em interação (39 espécies), totalizando 436 interações (82.20%). Seis espécies da subfamília Ponerinae foram responsáveis por 33 interações (6,4%). Myrtaceae foi a família de planta mais numerosa nas interações (14 espécies). Na segunda parte da tese, capítulos II e III, foi dado ênfase às duas espécies de formigas da subfamília Ponerinae (Pachycondyla striata e Odontomachus chelifer) onde investigamos a importância dos frutos na ecologia de forrageamento e desenvolvimento das colônias. No capítulo II nós estudamos como a estrutura dos ninhos, demografia das colônias, ritmo diário de atividades, dieta e área de vida dessas espécies variam espacial e sazonalmente em restinga e planície. Operárias de O. chelifer e de P. striata caçam de modo oportunista incluindo uma ampla variedade de itens alimentares, forrageando mais intensamente no período úmido quando alados são mais abundantes e as condições ambientais são mais favoráveis. A atividade de forrageamento apresentou variação entre as espécies de formigas, o que poderia ser associada com fatores físicos e disponibilidade de alimentos, mostrando que o comportamento de forrageamento de O. chelifer e P. striata corresponde a variabilidade temporal e espacial da Mata Atlântica. Para testar a hipótese de que o consumo de diásporos não-mirmecocóricos beneficiaria colônias de formigas, no Capítulo III nós testamos o efeito do consumo de sementes de C. canjerana, com arilos ricos em lipídeos, em colônias de O. chelifer sob condições controladas em laboratório. Constatamos que larvas de formigas alimentadas com diásporos de C. canjerana foram em média maiores e se desenvolveram melhor que larvas controle. Em conclusão, os resultados desta tese reforçam a importância da dispersão secundária por formigas para sementes primariamente dispersas por vertebrados. Os dados evidenciam também a importância do estudo da ecologia de forrageamento e da influência do consumo de frutos na sobrevivência e crescimento de colônias de formigas. / Abstract: The large number of fleshy fruits and the diversity and abundance of ants in tropical environments makes the ant-diaspore interaction very common. Currently it is known that these interactions involve a large number of plants and ants species in an ecological community. Among the ant species interacting with diaspores, Pachycondyla striata and Odontomachus chelifer stand out as main dispersers of seeds encountered on the forest ground. Moreover, the physical and chemical characteristics of their nests often promote the establishment of seedlings. However, despite the recognized importance of these ants for some species of plants, nothing is known about the influence of the consumption of fleshy diaspores in the development and reproduction of the ant colonies. Based on this scenario, this thesis was divided into two related parts. In the first part, Chapter I, we investigated the interactions between ants and nonmyrmecochorous diaspores in three different physiognomic forest of Cardoso Island (sandy, lowland and hillside), southeastern Brazil. During two years of monthly samples 517 interactions involving 53 ant species and 48 species of seeds were observed. Most interactions occurred in lowland Forest (54.62%), and less than half occurred in the two other areas, hillside (31.33%) and sandy Forest (14.06%). Myrmicinae had the highest species number in interaction (39 species), totaling 436 interactions (82.20%). The six species of the Ponerinae subfamily were observed exploring diaspores accounted for 33 interactions (6.4%). Myrtaceae was the most numerous plant family in interactions (14 species). In the second part of this thesis, Chapter II and III, we emphasized two species of Ponerinae (Pachycondyla striata and Odontomachus chelifer), investigating the importance of fruits in their foraging ecology and the development of their colonies. In Chapter II we studied how nest structure, colonies demography, daily activities, diet and home range of these two species vary spatially and seasonally in sandy and lowland forest. Odontomachus chelifer and Pachycondyla striata workers hunt opportunistically including a wide variety of food items. They forage more intensively during the wet season when alates are more abundant and environmental conditions are more favorable. The foraging activity showed variation among the ant species, which could be associated with physical factors and food availability, showing that the foraging behavior of O. chelifer and P. striata correspond to temporal and spatial variability of the Atlantic Forest. To test the hypothesis that the consumption of non-myrmecochorous diaspores benefit ant colonies, in Chapter III we tested the effect of consumption of seeds of Cabralea canjerana, with lipid-rich arils, in colonies of O. chelifer under controlled laboratory conditions. We found that ant larvae fed with diaspores of C. canjerana were on average larger and grew better than control larvae. In conclusion, the data presented here reinforce the importance of secondary dispersal by ants for seeds primarily dispersed by vertebrates. Our results also indicate the importance of studying the foraging ecology and the influence of fruit consumption on survival and growth of colonies of ants. / Doutorado / Ecologia / Doutor em Ecologia

Crabgrass is a warm-season annual species that has the potential to provide high-quality summer forage for ruminants in the transition zone between subtropical and temperate regions of the United States. Growing annual lespedeza in association with crabgrass may be beneficial due to nitrogen transfer from the legume to the grass. The objectives of the research reported in this thesis were to (1) determine the effects of pH on establishment and growth of crabgrass; and (2) evaluate the effects of lespedeza seeding rate and N fertilization treatment on the yield, botanical composition, and nutritive value of crabgrass-lespedeza mixtures. A greenhouse study was conducted using three soil pH levels of 4.8, 5.5, and 6.3. Crabgrass germination and root and shoot yields were not affected by soil pH values. A field study was conducted to evaluate the influence of six lespedeza seeding rates (0-28 kg ha-1) and two N fertilization treatments (140 kg total N ha-1 or zero N) on crabgrass-annual lespedeza mixtures. In most cases, increasing lespedeza seeding rate increased lespedeza in the sward. However, lespedeza rate had limited effect on yield and nutritive value of the mixture. Nitrogen fertilization increased crabgrass in the sward and total yield by as much as 46%. Responses of nutritive value parameters to N fertilization were variable and appeared linked to weather factors. In vitro true digestibilities ranged from 750 to 875 g kg-1, and were largely unaffected by N fertilization and seeding rate The results of these studies indicate that crabgrass could provide moderate amounts of highly digestible forage while growing on acidic soils commonly found in the southeastern United States. Annual lespedeza may be grown in association with crabgrass, but limited improvement in yield and nutritive value were found for this practice. / Master of Science

Very little is known about why and how the Parkinson's disease (PD) neurodegenerative process begins and progresses. In the course of developments for treatment of PD, the discovery of the inhibition of monoamine oxidase (MAO B) was a conceptual breakthrough, and has now been firmly established. MAO B has also been implicated in the neurodegenerative processes resulting from exposure to xenobiotic amines. For example, MAO B catalyzes the first step of the bioactivation of the parkinsonian inducing pro-neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Additional insight into the mechanism of catalysis of MAO B and the mechanism of neurotoxicity by MPTP is therefore very valuable in the pursuit of the treatment of PD. / Thesis (Ph.D. (Pharmaceutical Chemistry))--North-West University, Potchefstroom Campus, 2008.