No description available.

Since the 1970's there has been industrial interest in using microorganisms as microcapsules. The encapsulation of actives (e.g. flavours, drugs, perfumes) is a necessary process for pharmaceutical and food companies because the precious and often expensive ingredients must be protected from degradation and also released in a specific site or under a specific stimulus. Saccharomyces cerevisiae, baker's yeast, represents a first choice microorganism for the encapsulation of active ingredients. It is biodegradable and biocompatible with human digestion and skin, and can be produced in an easy and cheap way. A major part of this project has been dedicated to the development of robust methods of extraction and quantification of hydrophobic substances loaded inside yeast cells, which have been subsequently combined with an indirect, fluorescence-based method for the evaluation of the rate of loading of hydrophobic substances in the same cells. In particular, it has been found that this process reaches a limit in the maximal loading capacity of intact yeast cells, most likely reflecting the maximal volume of the lipid droplet organelles in which loaded hydrophobes accumulate. With the new on-line (fluorescence-based) and off-line (chromatography-based) methods developed here it has been established that the loading process fundamentally follows a diffusion model, in which the solubility in water determines the permeation of substances through the cell wall and ultimately their uptake by yeast cells. However, treating yeast cells with organic solvents like DMSO - a new approach introduced in Prof. Tirelli's lab to enhance the encapsulation of hydrophobes - completely changes the chemical-physical parameters of the encapsulation process. In DMSO-treated cells, substances are loaded fundamentally in response to their hydrophobicity. Conversely, once loaded, the same substances are released with a rate that is inversely proportional to their hydrophobicity, as observed by applying a novel approach to measure the release of hydrophobes encapsulated in yeast cells, either in the absence of presence of DMSO-treatment. In conclusion, the new evidence reported here clarifies basic aspects of hydrophobe encapsulation in intact yeast cells and will thus help improving future applications of these microcapsules as a valid, inexpensive and biocompatible drug delivery system.

>Magister Scientiae - MSc / Diabetes Mellitus is a major global health issue, affecting over 463 million adults in the world. Metformin is the standard drug administered to most people suffering fromdiabetes; however, this medication is contraindicated in many individuals, like most of the medicines developed to combat diabetes. Many diabetic patients turn to herbal medicines due to their renowned traditional use and fewer side effects.While the beneficial effects of phytotherapy are very evident, separation of nontoxic from toxic phytochemicals is still a challenge. Phytonanotherapy is a branch in nanotechnology that seeks to find the middle ground between the fast-acting mechanism of conventional drugs which also present with long lasting or severe toxic side effects, and the slowacting mechanism of phytotherapy which presents with less severe side effects. As such, the aim of this study was to pioneer the investigation of gold nanoparticles biosynthesized using the Carprobrotus edulis fruit aqueous extract (CeFe-AuNPs) as potential treatment for diabetes mellitus. Previously optimized conditions were used to synthesize CeFe-AuNPs which were concurrently characterized using UV-Vis, dynamic light scattering, High Resolution – Transmission Electron Microscopy and Fourier Transform Infrared Spectroscopy techniques. The physichochemical stability of CeFe-AuNPs in phosphate buffer saline, 0.5 % bovine serum albumin, water and 10 % NaCl was also investigated. The effect of CeFe and CeFe-AuNPs on glucose uptake by yeast cells was investigated using 5, 10 and 25 mM glucose reactions. Acute toxicity of CeFe and CeFe- AuNPs was conducted in female Wistar rats (n = 20) and major organs were analyzed through the haematoxylin-eosin stain. The anti-diabetic effects of the CeFe (200 and 400 mg/kg) and CeFe- AuNPs (100 and 200 mg/kg) were investigated in male Wistar rats divided into seven group (n = 6). Histopathology of the pancreas, and the serum insulin were determined.

No / We have used the budding yeast Saccharomyces cerevisiae to identify genes that may confer sensitivity in vivo to the antimalarial and cytotoxic agent cryptolepine. Five S. cerevisiae strains, with different genetic backgrounds in cell permeability and DNA damage repair mechanisms, were exposed to several concentrations of cryptolepine. Cryptolepine showed a relatively mild toxicity for wild-type strains, which was augmented by either increasing cell permeability ( erg6 or ISE2 strains) or disrupting DNA damage repair ( rad52 strains). These results are compatible with the ability of cryptolepine to intercalate into DNA and thus promote DNA lesions. The effects of low concentrations of cryptolepine (20% and 40% inhibitory concentrations [IC20 and IC40]) were analyzed by comparing the gene expression profiles of treated and untreated erg6 yeast cells. Significant changes in expression levels were observed for 349 genes (117 upregulated and 232 downregulated). General stress-related genes constituted the only recognizable functional cluster whose expression was increased upon cryptolepine treatment, making up about 20% of upregulated genes. In contrast, analysis of the characteristics of downregulated genes revealed a specific effect of cryptolepine on genes related to iron transport or acid phosphatases, as well as a significant proportion of genes related to cell wall components. The effects of cryptolepine on the transcription of iron transport-related genes were consistent with a loss of function of the iron sensor Aft1p, indicating a possible disruption of iron metabolism in S. cerevisiae. Since the interference of cryptolepine with iron metabolism is considered one of its putative antimalarial targets, this finding supports the utility of S. cerevisiae in drug-developing schemes.

No description available.

Made available in DSpace on 2014-06-11T19:30:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-07-03Bitstream added on 2014-06-13T21:00:44Z : No. of bitstreams: 1 rivera_ar_me_jabo.pdf: 341547 bytes, checksum: 35f0260fb3dc1acd91d7c35f7c4333d4 (MD5) / Universidade Estadual Paulista / O trabalho teve como objetivos avaliar o efeito do uso de monensina e de um complexo de leveduras, ácidos graxos poliinsaturados e aminoácidos (LAA) no consumo de matéria seca e nutrientes, na estimativa da digestibilidade ruminal, nos parâmetros de fermentação ruminal (pH, concentração de nitrogênio amoniacal e de ácidos graxos de cadeia curta), na população de protozoários e na produção de metanoo Foram realizados dois experimentos, no primeiro com seis bovinos anelorados, com peso médio de 530 kg, que foram tratados com 5g dia-1 de LAA ou monensina ou caulim usado como controle, adicionados à dieta base composta por feno de Tifton 85 (Cynodon Sppo) e concentrado, em uma relação 80:200 No segundo experimento foram testados os mesmos aditivos, usando a técnica de produção de gases in vitro para estimar a produção de gás metanoo O delineamento experimental usado foi em blocos casualizadoso Entre os resultados houve menor consumo de matéria seca e dos nutrientes (P<O,05) e maior produção de ácido propiônico (P<0,05) efeito da monensinao A digestibilidade da matéria seca e dos nutrientes não foi influenciada pela utilização dos aditivoso O pH e a concentração de nitrogênio amoniacal foram adequadas para o crescimento microbianoo A produção de metano não foi alterada usando aditivos. / The objetives of this work were to evaluate the effect of additives: monensin and yeast cells, insatured fatty acid, aminoacid complex on nutrient intake, nutrient digestibilities, ruminal parameters, protozoa population and methane production. Two experiments were conducted. One experiment, six beef cattle, 530 kg live weight, feeding hay (Cynodon Spp.) and concentrate (porportion 80:20) were used. Monensin or yeast cells, insatured fatty acid, aminoacid complex or caulim (control) were given daily (5g). Two experiment, same additives were used to estimate methane production using the gas production technique. The statistics model was random block. The nutrient intake decreased (P<0.05) and propionic acid increased (P<0.05) using monensin. There were no effect of additives on nutrient digestibilities. Ammonia nitrogen and pH were adequated for microorganisms growth. There were no effect of additives on methane production.

Orientadora: Telma Teresinha Berchielli Moreno / Banca: Alexandre Amstalden Moraes Sampaio / Banca: Simone Gisele de Oliveira / Resumo: O trabalho teve como objetivos avaliar o efeito do uso de monensina e de um complexo de leveduras, ácidos graxos poliinsaturados e aminoácidos (LAA) no consumo de matéria seca e nutrientes, na estimativa da digestibilidade ruminal, nos parâmetros de fermentação ruminal (pH, concentração de nitrogênio amoniacal e de ácidos graxos de cadeia curta), na população de protozoários e na produção de metanoo Foram realizados dois experimentos, no primeiro com seis bovinos anelorados, com peso médio de 530 kg, que foram tratados com 5g dia-1 de LAA ou monensina ou caulim usado como controle, adicionados à dieta base composta por feno de Tifton 85 (Cynodon Sppo) e concentrado, em uma relação 80:200 No segundo experimento foram testados os mesmos aditivos, usando a técnica de produção de gases in vitro para estimar a produção de gás metanoo O delineamento experimental usado foi em blocos casualizadoso Entre os resultados houve menor consumo de matéria seca e dos nutrientes (P<O,05) e maior produção de ácido propiônico (P<0,05) efeito da monensinao A digestibilidade da matéria seca e dos nutrientes não foi influenciada pela utilização dos aditivoso O pH e a concentração de nitrogênio amoniacal foram adequadas para o crescimento microbianoo A produção de metano não foi alterada usando aditivos. / Abstract: The objetives of this work were to evaluate the effect of additives: monensin and yeast cells, insatured fatty acid, aminoacid complex on nutrient intake, nutrient digestibilities, ruminal parameters, protozoa population and methane production. Two experiments were conducted. One experiment, six beef cattle, 530 kg live weight, feeding hay (Cynodon Spp.) and concentrate (porportion 80:20) were used. Monensin or yeast cells, insatured fatty acid, aminoacid complex or caulim (control) were given daily (5g). Two experiment, same additives were used to estimate methane production using the gas production technique. The statistics model was random block. The nutrient intake decreased (P<0.05) and propionic acid increased (P<0.05) using monensin. There were no effect of additives on nutrient digestibilities. Ammonia nitrogen and pH were adequated for microorganisms growth. There were no effect of additives on methane production. / Mestre

Thesis (Ph.D. (Pharmaceutical Chemistry)--North-West University, Potchefstroom Campus, 2009.

Thesis (Ph.D. (Pharmaceutical Chemistry)--North-West University, Potchefstroom Campus, 2009.

Within the dissertation thesis “Study of Biological Material Attributes by Using Image Analysis Methods”, attention is focused on monitoring of the application of image analysis methods, mostly a fractal analysis, in studying the properties of various yeast species. The thesis includes determining the number of yeast cells and vegetative propagation of yeast using fractal parameters – fractal measure D and fractal dimension K. Attention is also paid not only to the application of the existing image analysis methods, but also to their renovation. The obtained images were evaluated using the box counting method specified by implementation of wavelet transformation. To monitor yeast cells for a longer time, it was first necessary to prepare a suitable microscopic preparation. To distinguish live and dead cells, the following fluorescent dyes were used: acridine orange, fluorescein diacetate, FUN-1, and Calcofluor White M2R. The images of yeast cells were recorded using a still camera or a CCD camera and microscope. Clips of the same size were obtained from the acquired digital photographs and processed by the HarFA program developed at the Faculty of Chemistry, Brno University of Technology. On the results it is possible to see a change in the fractal dimension depending on time, i.e. on the change of a budding cell structure, or to determine the number and radius of yeast cells upon predefined conditions.