The generation of high affinity, selective, and in vivo-stable peptide-based drugs is currently a major challenge in the field of drug development. Technologies exist that permit the generation of a vast diversity of chemical and conformational space and an example of such a technology is mRNA display, which utilizes protein translation machinery to produce a wide array of polypeptides starting from a combinatorial library of mRNA templates. The intention of this research was to bridge mRNA display to a reconstituted translation system using protein synthesis using recombinant elements (PURE) system for a new drug discovery platform. We hypothesized that it is possible to generate mRNA-peptidomimetic fusions using reconstituted translation system and chemo-enzymatically charged tRNAs, to incorporate unnatural amino acids into mRNA-peptidomimetic fusions. Upon demonstating that the reconstituted system was functional, we have synthesized hexapeptide fusion products containing four alanine residues and one biocytin residue. Fusions were assayed using urea-PAGE in the presence of streptavidin which allowed for unambiguous evaluation of the full length fusion fraction. It was determined that overall more fusion product was generated with template that codes for biocytin early in the coding sequence, but that the percent of biocytin-containing product stays similar regardless of the biocytin place in the coding region. We have also found that the change in template untranslated region length does not improve incorporation of biocytin in dipeptide fusions within the tested range. Finally, after first unsuccessful attempts to make sarcosine hexapeptide fusions, we investigated the effect of magnesium ion concentration on the translation reaction. As a result of four series of experiments performed involving both alanine and sarcosine fusion synthesis in parallel, we concluded that an increase in magnesium concentration from 5 mM to 20 mM coincided with enabling of the reconstituted system in making hexapeptide fusions with sarcosine in a significantly high number of cases. This research work arises from the need to enable a new drug discovery tool that will allow both synthesis and affinity maturation of peptide-based compounds. It represents our pioneering efforts to develop a new technology and ultimately help bring to existence compounds of significant therapeutic value.

The aim of this project was to study the in vitro release of cephalothin, vancomycin and strontium from hydroxyapatite particles and its PMMA composite. The hydroxyapatite spheres containing strontium were prepared in the laboratory. The in vitro release study for the hydroxyapatite was carried out in phosphate buffer saline solution (PBS) with differing pH value at 37 °C for five days and the PMMA composites for 21 days. All of the releases showed a burst release within the first 24 hours followed by a slow release. The pH value of the release medium had influence on the release rate to some extent for the antibiotic release and the acidic solution had a more significant impact on the strontium release. All of the composite groups had a much lower strontium release rate than the strontium release from the hydroxyapatite spheres.

This thesis proposes a multi-parameter implantable micro-stimulator system. By using wireless communication and the muli-parameter control, the infection caused by the wound could be avoided and various stimulation waveforms could be generated for different bio-medical applications. Besides, a graphic user interface (GUI) is implemented for the proposed micro-stimulator for the convenience of usage. Moreover, the in vitro experiments are carried out, where the neurons could be stimulated successfully. To reduce the system area caused by external capacitors required by traditional ASK demodulators, a C-less ASK demodulator is proposed in this thesis. A bias-based envelope detector and a Schmitt trigger are used for demodulation. Moreover, by enlarging the noise margin of the envelope detector, an all-MOS ASK demodulator is carried out such that no passive element is needed and the system area could be further reduced. Besides, two high sensitivity voltage-to-frequency (VFC) are proposed for the full duplex transmission. By using a voltage-to-current converter, a charge and discharge circuit, and an all-MOS voltage window comparator 1 (VWC1), a high sensitivity VFC1 is accomplished. Moreover, a linear VFC2 is also proposed by including a fast all-MOS voltage window comparator, VWC2. Finally, a wide range I/O buffer is proposed for the interface of the implantable micro-stimulator system. With the stacked PMOS and NMOS output stage and the dynamic gate bias generator, high voltage and low voltage signals (VDDH and VDDL) could be transmitted and received without any gate-oxide overstress and leakage currents.

Thèse d'exercice : Pharmacie : Université de Nantes : 2003. / Bibliogr. f. 74-76 [36 réf.].

published_or_final_version / abstract / toc / Medicine / Master / Doctor of Medicine

Field performance of micropropagated (MP) and conventionally propagated (CP) red raspberry (Rubus idaeus L. cv. Comet and Festival) was examined under hedgerow and stool cane management systems for 3 seasons (1989 to 1991). All MP plants established well compared to 58% survival rates 45 days after planting and 92% survival rates after replanting for CP plants. The MP plants were more vigorous compared with the CP plants for the duration of this study as indicated by more and taller canes. MP 'Festival' in 1990 yielded 2.2 MT$ cdot$ha$ sp{-1}$, almost half the yield of established commercial plantings in Quebec, while yields from CP 'Festival' and MP and CP 'Comet' were negligible. The MP 'Festival' crop (8.42 MT$ cdot$ha$ sp{-1}$) also outyielded CP 'Festival' (6.8 MT$ cdot$ha$ sp{-1}$) and both MP (5.72 MT$ cdot$ha$ sp{-1}$) and CP (4.91 MT$ cdot$ha$ sp{-1}$) 'Comet' in the second fruiting year. Propagation method had no effects on winter hardiness, photosynthetic capacity nor leaf and stem morphology of either cultivar. The results indicated that MP plants were superior to CP plants for both nursery propagation and fruit production due to their more consistent establishment and increased vigor. Red raspberry plantlets were successfully hardened in vitro on low-sucrose or sucrose-free media through CO$ sb{2}$ enrichment (1500 ppm) and relative humidity reduction (90%) using a forced ventilation system in specially constructed plexiglass chambers. Enriched CO$ sb{2}$ significantly increased general vigor, root formation, root growth, plantlet growth and plantlet photosynthetic capacities. Sucrose in the medium promoted plantlet growth but depressed photosynthesis. In vitro relative humidity at 90% decreased stomatal apertures and improved plantlet ex vitro performance but did not affect the CO$ sb{2}$ uptake rates of cultured plantlets or ex vitro transplants. The maximum CO$ sb{2}$ uptake rates of plantlet leaves were about 52-69% that of greenhouse control pla

The generation of high affinity, selective, and in vivo-stable peptide-based drugs is currently a major challenge in the field of drug development. Technologies exist that permit the generation of a vast diversity of chemical and conformational space and an example of such a technology is mRNA display, which utilizes protein translation machinery to produce a wide array of polypeptides starting from a combinatorial library of mRNA templates. The intention of this research was to bridge mRNA display to a reconstituted translation system using protein synthesis using recombinant elements (PURE) system for a new drug discovery platform. We hypothesized that it is possible to generate mRNA-peptidomimetic fusions using reconstituted translation system and chemo-enzymatically charged tRNAs, to incorporate unnatural amino acids into mRNA-peptidomimetic fusions. Upon demonstating that the reconstituted system was functional, we have synthesized hexapeptide fusion products containing four alanine residues and one biocytin residue. Fusions were assayed using urea-PAGE in the presence of streptavidin which allowed for unambiguous evaluation of the full length fusion fraction. It was determined that overall more fusion product was generated with template that codes for biocytin early in the coding sequence, but that the percent of biocytin-containing product stays similar regardless of the biocytin place in the coding region. We have also found that the change in template untranslated region length does not improve incorporation of biocytin in dipeptide fusions within the tested range. Finally, after first unsuccessful attempts to make sarcosine hexapeptide fusions, we investigated the effect of magnesium ion concentration on the translation reaction. As a result of four series of experiments performed involving both alanine and sarcosine fusion synthesis in parallel, we concluded that an increase in magnesium concentration from 5 mM to 20 mM coincided with enabling of the reconstituted system in making hexapeptide fusions with sarcosine in a significantly high number of cases. This research work arises from the need to enable a new drug discovery tool that will allow both synthesis and affinity maturation of peptide-based compounds. It represents our pioneering efforts to develop a new technology and ultimately help bring to existence compounds of significant therapeutic value.

No description available.

Follicular antral oxygen tension is thought to influence subsequent oocyte developmental competence. Despite this, in vitro maturation (IVM) is routinely performed in either 5 or 20% oxygen and while low oxygen has been shown to be beneficial to embryo development in many species, the effects of altering oxygen concentration during IVM have not been adequately investigated. Here we investigated the effects of a range of oxygen concentrations (2, 5, 10 & 20% oxygen) during IVM of mouse oocytes on a range of oocyte and embryonic parameters as well as fetal/placental outcome measures and cumulus cell gene expression. While common short term measures of oocyte developmental competence such as maturation, fertilisation, and embryonic development rates were not affected over the range of oxygen levels used, more in depth investigations found several striking differences. Following IVM at 5% oxygen, the oocyte mitochondria were found to have altered patterns of both membrane potential (a measure of mitochondrial activity) and distribution suggesting altered oocyte metabolism. Following IVF, the cellular make up of embryos was investigated. In blastocysts derived from low IVM oxygen (2%) there was found to be an increased number of trophectoderm cells, an increased level of apoptosis (although this was not of sufficient magnitude to account for the cell number difference) and more cells positive for both Cdx2 and Oct4 (markers of trophectoderm and inner cell mass cell types respectively) suggesting a less differentiated cell type. Furthermore, following embryo transfer, the ability of the embryos to implant or develop was not altered by IVM oxygen concentration; however, fetal and placental weights were reduced in the 5% oxygen group. Cumulus cell gene expression was also examined and was found to be altered both across IVM oxygen treatment groups and when compared to cells isolated from in vivo derived complexes. This change in gene expression elucidates some of the many ways in which oxygen concentration during IVM may be affecting the cumulus-oocyte complex (COC) and its future development. Together, this data highlights the importance of looking past common outcome measures when determining the effects of IVM culture conditions. The results of this study also suggest that while IVM oxygen concentration contributes to the perturbing nature of current IVM systems, it is only one of many constituents that require proper investigation, understanding and optimisation. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1368831 / Thesis (Ph.D.) -- University of Adelaide, School of Paediatrics and Reproductive Health, 2009

Thesis (M. Phil.)--University of Hong Kong, 2007. / Also available online.