The main objective of the study was to characterise, by electron spin resonance (ESR) spectroscopy, novel halogen containing a* radicals. These species are formed by ?-irradiation in a variety of halogen containing systems at liquid nitrogen temperatures. In Chapter One, a brief description of the first halogen a* radical to be identified, the Vx centre in potassium chloride (C12.-), is given in order to illustrate the general magnetic properties of the species. The dependence of these properties on the host matrix is also described. Accepted radiation damage mechanisms are presented with particular reference to dihalogen a* radicals. Some theoretical aspects of the ESR experiment is discussed in Chapter Two which explains briefly some of the phenomena encountered in the study. Sample preparation and analysis are also mentioned. Chapter Three describes the characteristics of the simplest halogen containing a* radical: the hydrogen halide radical anion. Hydrogen fluoride, hydrogen chloride, hydrogen bromide and hydrogen iodide radical anions isolated in a variety of host matrices are reported. The large matrix dependence of their magnetic parameters is explained in terms of intermolecular hydrogen bonding to the halogen. Attention is focused on nitrogen-halogen a* radicals in Chapter Four, where they are shown to be radiolytically formed in ammonium halides, mono, di and trialkylammonium iodides and monoalkylammonium bromides. Alkylamanium chloride radicals could not be identified. Chapter Five primarily explores the effect of the halide counter ion on the solid-state radiolysis of some tetraalkylammonium, trialkylsulphonium and trialkylsulphoxonium cations. During the course of the investigation, sulphur-halogen a* radicals are identified in the trialkylsulphonium salts after annealing. The last chapter investigates the factors which determine the type of species formed following electron capture by carbon halogen bonds. Both adducts and a* radicals are characterised and with particular reference to the specific example of iodoacetamide, consideration is given to the factors influencing their stability.

No description available.

No description available.

The present investigation was undertaken in order to assess the clinical effects of prostaglandins and to evaluate their role in present modern day obstetrics. To this end pertinent clinical and laboratory studies were carried out. This has not been done before in the Republic of South Africa. It is considered that the following contributions to knowledge have been made: 1. In comparable patients prostaglandin F 2a and oxytocin are equally effective in labour induction at term. 2. Prostaglandin F2a is more effective in labour induction where the cervix is unripe and amniotomy is performed. 3. Amniotomy statistically significantly increases the success rate of induction of labour where prostaglandin F2a is used as the oxytocic agent. 4. Amniotomy statistically significantly accelerates labour in both prostaglandin F2a and oxytocin induction, using labour parameters for comparison which have been devised and are described in the text. 5. Comparable titration schedules of prostaglandin F2a and oxytocin have been devised for labour induction. 6. Prostaglandin F2a is not antidiuretic when used to induce patients with classical pre-eclampsia as compared with oxytocin. 7. Prostaglandins are implicated in the acceleratory phase of normal labour. 8. The only statistically significant side effect produced by prostaglandin F2a when compared with oxytocin is a transient red line in the skin along the area draining the site of the intravenous infusion. 9. Prostaglandin F2a does produce a coordinate form of labour if certain precautions are adhered to. 10. Effacement of the cervix in the latent phase has been measured and may be used in order to predict the rate of progress in the first stage of labour in primigravidae. The results are presented in the text.

Salley in 1954, (122) was the first worker to use the hamster cheek pouch as a model for experimental carcinogenesis and to produce squamous cell carcinomas in this organ. For a number of reasons, the pouch is most suitable for sequential studies of carcinogenesis, and these include the fact that it is easily accessible and can be everted simply, facilitating macroscopic examination. Furthermore, its anatomic situation makes it a simple model for topical application of any carcinogen. Each animal has two pouches, thus providing its own control. In addition, the pouch serves as a storehouse and is lined only by stratified squamous epithelium with no glands or hair follicles in its wall, thus rendering it less susceptible to cyclic changes than more complex tissues, in which accessory structures are present.

Aquaculture methods are limited for white crappie (Pomoxis annularis), reducing production potential. Therefore, reproduction methods, including induced spawning, sperm cryopreservation and out-of-season spawning, were developed in tank systems. A two week acclimation period (15°C; 3-5 ppt salinity) was necessary to reduce disease-related mortality. Afterwards, four spawning induction hormones and a control were examined to induce spawning. Luteinizing hormone releasing hormone analogue and salmonid gonadotropin releasing hormone analogue performed the best in terms of spawning success and %ertilization. Sperm cryopreservation was effective using Hanks or Ca2+ree Hanks balanced salt solutions with 10%-methanol or 5%-dimethyl-sulfoxide as a cryoprotectant, frozen at 40°C/min. Out-of-season spawning experiments manipulated photoperiod and temperature over 3-wk (9% spawning success; 11% fertilization) and 6-wk (16% spawning success; 55% fertilization) seasonal shifts. Post-experiment maturation data indicate that females were in an intermediate development stage. These experiments demonstrate the potential of advanced spawning techniques to improve annual production of white crappie.

This thesis describes the design and construction of a portable laser induced fluorescence sensor. The objective was to create a low-cost, versatile, and modular laser induced fluorescence sensor for agricultural remote sensing. The sensor module should able to be integrated with different pieces of hardware. The objective was successfully accomplished with the creation of a sensor module that met all of the requirements. The sensor module integrates with a handheld unit for reading and visualizing the data that was constructed and is described in this work. Performance testing and experiments were carried out with the sensor module in the handheld device with a focus on plant physiology. In particular, chlorophyll fluorescence related to stress and ripeness was studied and fungal toxins found in corn were detected with this device. Ongoing work consisting of mounting the sensor module to an unmanned aerial vehicle and testing in flight is described.

The innate immune system is the first line of defence against viral infections. Conventionally, innate immune activation begins with the detection of foreign nucleic acids by pattern recognition receptors (PRRs), which triggers a signalling cascade that culminates in the production of interferon (IFN) and other inflammatory cytokines and chemokines. Over the past few years, a number of studies have shown that IFN innate immune responses can also be triggered by stressors, such as membrane perturbations, cytoskeletal perturbations, oxidative stress, and endoplasmic reticulum (ER) stress 1–3. One way that some viruses provoke such stress responses is through membrane and cytoskeletal distortions during enveloped virus particle entry. In some cases, the glycoproteins responsible for virus particle entry can also trigger cell-cell fusion. The potential of cell-cell fusion to induce stress-based IFN responses analogous to those triggered by virus-cell fusion has not been addressed until very recently. To investigate if and how cell-cell fusion may induce antiviral mechanisms and IFN responses we used the reptilian reovirus p14 fusion associated small transmembrane (FAST) protein as a model of cell-cell fusion. We found that p14-mediated cell fusion led to the production of low level IFN and upregulation of interferon stimulated genes (ISGs) in a stimulator of interferon genes (STING) and interferon regulatory factor 3 (IRF3) dependent manner. We also observed that multinucleated cells experienced extensive DNA-damage that led to the accumulation of cytosolic DNA in the form of micronuclei. Micronuclei can be detected by cytosolic DNA PRRs like cyclic GMP-AMP synthase (cGAS) and signal IFN production through the cGAS-STING signalling axis. Additionally, early syncytia formation restricted replication of vesicular stomatitis virus (VSV), herpes simplex virus-1 (HSV), and vaccinia virus (VSV) in an IFN and IRF3 independent, and STING dependent manner, suggesting involvement of either a novel antiviral mechanism or suppression of virus replication and spread by biological changes in syncytial cells, such as cell cycle arrest. This study highlights a key role of DNA sensing pathways in the immune response to cell fusion associated stress and points out the importance of fusion kinetics in the selective advantage of syncytial viruses. Understanding the potential of syncytial cells to induce IFN responses and influence viral replication at a mechanistic level is beneficial to the design of improved oncolytic immunotherapy. / Thesis / Master of Science (MSc) / Viruses and their hosts continuously fight each other for survival. The host tries to protect itself from the virus by activating various features of its immune system, while the virus tries to block and evade detection by the immune system. One way that some viruses attempt to bypass the immune system and enhance spread involves expressing proteins that can merge together infected cells with neighboring uninfected cells. Cell-cell fusion disrupts the balanced environment within the cell, which is a form of stress that may activate immune responses. This work investigates if and how host cells may activate the immune system to respond and protect themselves from the cell merging activity of select viruses. We found that the stress associated with existing as a large, fused cell caused DNA damage and fragmentation. These DNA fragments could stimulate key immune sensors and initiate immune responses. We also observed an impaired ability of viruses to infect fused cells, but this restriction was not associated with typical immune responses, suggesting that some other biological change in fused cells created an environment that is not suitable for viral spread. Further investigation is required to fully understand this phenomenon; however, this study highlights some protective mechanisms of the host immune system in response to the stress of viral fusion protein induced cell-cell fusion.

Induced pluripotent stem (iPS) cells that possess embryonic stem (ES) cell-like properties are generated through the use of the Yamanaka transcription factors, OCT4, SOX2, KLF4, and MYC (OSKM). Advanced transgene delivery methods utilizing non-integrating viruses for transduction of target cells has provided new opportunities for regenerative medicine in humans and other species. We sought to use this technology to generate equine iPS cells to address challenges in equine regenerative medicine. Umbilical cord matrix mesenchymal stromal cells (MSC) were transduced with the non-integrating Sendai virus encoding for the OSKM transcription factors. The cells initially were cultured on mouse embryonic feeder cells supplemented with LIF (10 ng/mL) and FGF2 (4 ng/mL). Transduction generated 21 initial colonies. Of these, four survived beyond 20 passages. The transduced equine cells morphologically resembled ES cells and expressed cell surface antigens indicative of ES cells. Molecular evaluation revealed the cells maintained expression of endogenous OSKM while the exogenous OSK transgenes were extinguished, but MYC was maintained. The transduced equine cells did not express the ES marker NANOG, but did express the trophectoderm markers CDX2 and TFAP2A. Both OCT4 and CDX2 were colocalized to the nucleus. The transduced equine cells were termed equine induced trophoblast (iTr) cells. Culture of the iTr cell in suspension resulted in formation of blastocyst-like spheres rather than solid cell aggregates indicative of ES and iPS cells. The iTr cells were transitioned to a feeder free monolayer culture. Transformation of the iTr cells to the spherical arrangement stimulated expression of genes that mark differentiation of trophoblast cells and up-regulated 250 transcripts over the monolayer arrangement. The iTr monolayer arrangement up-regulated 50 transcripts compared to the spherical arrangement. The iTr spheres respond to BMP4, EGF, and FGF2 by phosphorylating signal transduction proteins. Addition of BMP4, EGF, or FGF2 in combined pairs was able to alter TFAP2A, NEU1, and SLC35A1 expression. The generation of iTr cells by transduction of the Yamanaka reprogramming factors is not unique to equine cells. However, this report marks the generation of the first equine trophoblast cell line capable of recapitulating early equine trophoblast development. The new iTr line could prove valuable in gaining greater understanding of equine trophectoderm development. / Ph. D.

Laser Induced Breakdown Spectroscopy LIBS is a fast non-contact technique for the analysis of the elemental composition using spectral information of the emission from a laser-induced plasma. For the LIBS studies in this thesis the focus has been in using very low energy, microjoule pulses in order to give high spatial resolution and minimize the laser system requirements. This is a regime that we refer to as microLIBS. Under such conditions it is important to maximize the signal detected to give the lowest limit of detection LOD possible. One technique to improve the signal to noise ratios is by coupling LIBS with Laser Induced Fluorescence. This is a technique where the _rst pulse creates a vapor plume and the second pulse tuned to a resonant absorption line of the species of interest re-excites the plume. We term this technique as Laser ablation Laser Induced Fluorescence LA-LIF. We have been investigating the performance of LA-LIF at low pulse energies (_ 1 mJ for both pulses) for the detection of elemental contaminants in water. This technique allows reasonable performance compared to high energy singlepulse LIBS, but at a much reduced total energy expenditure. This allows LODs in the parts per billion range ppb range which typically cannot be obtained with low energy single pulse probing of the systems. This approach or exceeds the sensitivities which can be obtained with many shots using much larger energy systems. In this thesis we investigated the performance of LIBS at low pulse energies for the detection of Pb as a contaminant in water. An LOD of 70 ppb was obtained for an accumulation of 100 shots with the ablation laser pulse energy of 250 _J and an excitation laser pulse energy of 8 _J. A systematic study of the detector conditions was made for the system for the detection of Pb. Scaling laws for the LOD in terms of the pump and probe energies were measured and also the e_ect of detector gain, the gate delay and the gate width were studied. In this thesis LIBS and LA-LIF were also used to analyze ultralow volumes of analyte in liquids in microuidic geometries. LIBS was applied for the detection of Na in liquid droplets in a microuidic system. The detection of Na as low as 360 femtograms was demonstrated for 100 shots integrated in this system. An LOD of 7 ppm for Pb for 100 shot accumulation was demonstrated using the LA-LIF technique on an 18 _m diameter microdroplet. To study the laser interaction with the water targets the MEDUSA one dimensional hydrocode was used. The propagation of the shockwave and plume dynamics were studied using this modeling code. The expansion of the plume was studied and compared to experimentally measured values and to physical models for blast wave expansion and stagnation. Two preconcentration techniques were also studied, one of which used a wood-chip as a substrate to absorb the analyte liquid and wick the salt on to the surface for analysis and the other used an electroplating technique to plate the analyte metal as a thin _lm on a substrate metal used as a cathode. The electroplating method for preconcentration was also studied using a microchip laser and a LOD of 6.4 ppb for Pb in water was obtained for an accumalation of 200,000 shots. / Photonics and Plasmas