Sweet potato is one of the 15 most important food crops worldwide. At least 30 different virus species, belonging to different taxonomic groups affect sweet potato. Little is known about the viruses present in sweet potato crops in Central America, which is the primary origin of sweet potato. The objective of this study was to design and implement primers for use in polymerase chain reaction (PCR) and Reverse transcription-PCR (RT-PCR) to identify and survey the diversity of plant viruses infecting sweet potato in Honduras and Guatemala. Primers were designed and used to amplify, clone, and sequence a taxonomically informative fragment of the coat protein (CP) gene for whitefly-transmitted geminiviruses (herein, sweepoviruses) and potyviruses, and of the heat shock protein 70 (HSP70) for the Crinivirus, Sweet potato chlorotic stunt virus (SPCSV). The partial genome sequences were used for identification based on phylogenetic relationships with reference sequences available in the GenBank database. All three of the plant virus groups identified in this study were found to occur either in single or in multiple infections. Results of the sequence analyses indicated that the genomic regions amplified in this study were capable of discriminating among potyvirus species, and strains of SPCSV. With respect to potyvirus, all isolates were identified as Sweet potato feathery mottle virus (SPFMV) species, except for two, which grouped phylogenetically with Sweet potato virus G (SPVG) and Sweet potato virus C (SPVC). All sweepoviruses detected in sweet potato plants belonged to a single phylogenetically, well-supported group that contains all other previously described geminiviruses (sweepoviruses) associated with sweet potato or closely related host species. These results demonstrate that the primers designed for amplification of plant virus species commonly recognized to infect sweet potato, effectively detected the viruses singly and in mixtures from symptomatic plants, and that the resultant fragment, when subjected to cloning and DNA sequenced, was phylogenetically informative at the species and/or strain levels, depending on the virus group.

HER2/neu is an oncogenic tumor-associated antigen over-expressed in several human tumors including breast and ovarian cancer. The selective expression of HER2/neu and its role in epithelial carcinogenesis makes HER2/neu an ideal target for immunotherapy. Tumor-derived chaperone-rich cell lysate (CRCL), containing numerous heat shock proteins, has successfully been used to generate tumor-specific immunity against a wide range of murine tumors and is a great candidate for an effective vaccine against HER2/neu positive tumors. In the first part of this study, the potency of human ovarian cancer-derived CRCL to activate dendritic cells (DCs) and to generate tumor-specific T cells in vitro has been investigated. Chaperone-rich cell lysate was generated from primary ovarian cancer tissues and SKOV3-A2, a HER2/neu, Wilm's tumor gene 1 (WT1) and HLA-A2 positive human ovarian tumor cell line. T cells from healthy donors and from ovarian cancer patients secreted higher amounts of interferon-γ following in vitro re-stimulation with ovarian cancer-derived CRCL compared to HER2/neu or WT1 peptide-pulsed DCs. We were also able to generate cytotoxic T lymphocyte activity against cancer-specific antigens such as HER2/neu and WT1 from all healthy donors, but from only one of the four ovarian cancer patients with bulky disease. In the second part of the study, the potency of tumor-derived CRCL to elicit the humoral immune response against a murine HER2/neu positive tumor (TUBO) has been examined. Vaccination of mice bearing a palpable tumor efficiently delayed the development of the tumor. In the vaccinated mice, CRCL vaccination induced significant anti-HER2/neu antibodies. Using B cell deficient mice and antibody transfer experiments, we have shown that the induction of anti-HER2/neu antibodies is both necessary and sufficient for the anti-tumor effect. Further, we have demonstrated that serum from TUB0 CRCL-vaccinated mice stimulated the internalization of the HER2/neu molecules, resulting in the down-regulation of their surface expression. Moreover, antibody-dependent cellular cytotoxicity has been observed against TUBO cells when presented with sera from vaccinated mice. These results indicate that CRCL may be a potent adjuvant for women suffering from HER2/neu positive ovarian or breast cancer and that this personalized vaccine may be a promising approach for active immunotherapy.

One unique feature of cancer cells that can be exploited for anticancer drug discovery is their dependence on their own cellular stress responses to survive the stressful acidotic, hypoxic and nutrient-deprived conditions within the tumor. Reasoning that desert organisms surviving under stressful conditions may have evolved to produce small molecule metabolites capable of modulating heat shock protein 90 (Hsp90) function, and/or other cell stress responses, we employed the cellular heat shock response in a moderate-throughput phenotypic assay. This strategy has resulted in the isolation and characterization of a number of small molecule natural products with heat shock induction activity from these organisms. Three such natural products are the subject of this study.In a limited structure-activity relationship (SAR) study, a previously known Hsp90 inhibitor radicicol (RAD), and several structurally related molecules including the fungal metabolite monocillin 1 (MON) were found to interact with Hsp90. In addition, RAD and MON were shown to lead to the degradation of Hsp90 client proteins involved in the cancer cell survival the estrogen receptor (ER) and the insulin-like growth factor receptor 1 (IGF-1R).We further characterized MON and showed that by targeting the molecular chaperone Hsp90, this compound induces components of the heat shock response at the transcriptional and translational levels, and leads to the acquisition of a thermotolerant phenotype in seedlings of the plant Arabidopsis thaliana. These findings support our hypothesis that there is ecological significance to the elaboration of small molecules that target stress responses.A number of extracts active in our phenotypic assay contained small molecules with no apparent Hsp90 activity. One such extract afforded terrecyclic acid A (TCA) with significant anti-tumor activity against a panel of human cancer cell lines. To characterize the biological activities of TCA we examined three key stress responsesthe heat shock, oxidative, and inflammatory responsesand show that TCA destabilizes these pathways associated with cancer cell survival through induction of oxidative stress (ROS), and inhibition of NF-kappaB transactivation.The isolation of RAD, MON and TCA from Sonoran desert organisms provides proof of principle that we have developed an effective strategy for the discovery of small molecule modulators of cellular stress responses that can serve as leads for the development of new anticancer drugs with novel mechanisms of action.

Septic shock is frequently seen in intensive care units and is associated with significant mortality. Endotoxin – a major mediator of the pathophysiologic responses – is released during lysis of Gram-negative bacteria. These responses can be mimicked in the endotoxaemic pig. This thesis focuses on the following topics: the inflammatory and pathophysiological responses to various endotoxin doses and infusion patterns; covariations between endotoxin induced inflammatory and pathophysiological responses; whether the biological effects of endotoxin can be modulated by clopidogrel and whether tobramycin or ceftazidime reduce plasma cytokine levels. Endotoxin induced linear log-log cytokine and F2-isoprostane responses. Leukocyte and platelet responses, pulmonary compliance, circulatory variables as well as indicators of plasma leakage and hypoperfusion exhibited log-linear responses to the endotoxin dose. Biological responses to endotoxaemia such as inflammation, hypotension, hypoperfusion and organ dysfunction were more expressed when the organism was exposed to endotoxin at a higher rate. These results may facilitate the possibility to choose relevant endotoxin administration, when experiments are set up in order to evaluate certain responses to endotoxaemia. Correlation studies between cytokines, leukocytes, platelets and the endotoxin dose were in agreement with the well-known ability of endotoxin to induce cytokine expression and to activate both primary haemostasis and leukocytes. Free radical mediated lipid peroxidation and COX-mediated inflammation correlated to cytokine expression and organ dysfunction in endotoxaemic shock. Endotoxaemic pigs pretreated with clopidogrel, exhibited a trend towards less expressed deterioration of renal function, although blocking of ADP-induced primary haemostasis is not a key mediator of endotoxin induced deterioration of renal function. Tobramycin did not neutralise the biological effects of endotoxin or the plasma levels of endotoxin, suggesting that these antibiotics do not bind to endotoxin. Reduction in IL-6 was greater in pigs treated with ceftazidime and tobramycin as compared with those given saline, indicating a possible anti-inflammatory effect of both antibiotics.

The interest in the role of the solar wind termination shock (TS) and heliosheath in cosmic ray (CR) modulation studies has increased sigm6cantly as the Voyager 1 and 2 spacecraft approach the estimated position of the TS. For this work the modulation of galactic CR protons, anti-protons, electrons with a Jovian source, positrons, Helium, and anomalous protons and Helium, and the consequent charge-sign dependence, are studied with an improved and extended two-dimensional numerical CR modulation model including a TS with diffusive shock acceleration, a heliosheath and drifts. The modulation is computed using improved local interstellar spectra (LIS) for almost all the species of interest to this study and new fundamentally derived diffusion coefficients, applicable to a number of CR species during both magnetic polarity cycles of the Sun. The model also allows comparisons of modulation with and without a TS and between solar minimum and moderate maximum conditions. The modulation of protons and Helium with their respective anomalous components are also studied to establish the consequent charge-sign dependence at low energies and the influence on the computed p/p, e-/p, and e-/He. The level of modulation in the simulated heliosheath, and the importance of this modulation 'barrier' and the TS for the different species are illustrated. From the computations it is possible to estimate the ratio of modulation occurring in the heliosheath to the total modulation between the heliopause and Earth for the mentioned species. It has been found that the modulation in the heliosheath depends on the particle species, is strongly dependent on the energy of the CRs, on the polarity cycle and is enhanced by the inclusion of the TS. The computed modulation for the considered species is surprisingly different and the heliosheath is important for CR modulation, although 'barrier' modulation is more prominent for protons, anti-protons and Helium, while the heliosheath cannot really be considered a modulation 'barrier' for electrons and positrons above energies of ~150 MeV. The effects of the TS on modulation are more pronounced for polarity cycles when particles are drifting primarily in the equatorial regions of the heliosphere along the heliospheric current sheet to the Sun, e.g. the A < 0 polarity cycle for protons, positrons, and Helium, and the A > 0 polarity cycle for electrons and anti-protons. This study also shows that the proton and Helium LIS may not be known at energies <~ 200 MeV until a spacecraft actually approaches the heliopause because of the strong modulation that occurs in the heliosheath, the effect of the TS, and the presence of anomalous protons and Helium. For anti-protons, in contrast, these effects are less pronounced. For positrons, with a completely different shape LIS, the modulated spectra have very mild energy dependencies <~ 300 MeV, even at Earth, in contrast to the other species. These characteristic spectral features may be helpful to distinguish between electron and positron spectra when they are measured near and at Earth. These simulations can be of use for future missions to the outer heliosphere and beyond. / Thesis (Ph.D. (Physics))--North-West University, Potchefstroom Campus, 2004.

Bei Patienten mit akut dekompensierter Herzinsuffizienz beziehungsweise kardiogenem Schock ist die Kurz- und die Langzeitprognose stark reduziert. Ziel dieser prospektiv klinischen Studie war die Feststellung des Maximums des NTproBNP-Wertes in der Akutphase innerhalb der ersten zwölf Stunden nach Krankenhausaufnahme sowie die Untersuchung der NTproBNP-Spiegel als Prädiktor der 18-Monatsmortalität in dieser Patientengruppe. Es wurden insgesamt 148 Patienten in zwei Studienabschnitten eingeschlossen, wobei die Kurz- und Langzeitverläufe aller Patienten zu den Zeitpunkten 0, 12, 24 und 48 Stunden, 7 und 14 Tagen sowie 1, 3 und 18 Monaten untersucht wurden. Bei 32 Patienten wurden zusätzlich regelmäßige zweistündliche Untersuchungen der NTproBNP-Werte innerhalb der ersten zwölf Stunden (2, 4, 6, 8 und 10 Stunden nach Aufnahme) durchgeführt. Für Patienten mit akut dekompensierter Herzinsuffizienz bzw. kardiogenem Schock ohne akuten Myokardinfarkt fanden sich innerhalb der ersten zwölf Stunden keine siginifikant erhöhten NTproBNP-Plasmaspiegel im Vergleich zum Aufnahmewert, eine statistische Signifikanz bezüglich der 18-Monatsmortalität fand sich in dieser Gruppe innerhalb der ersten 48 Stunden nur zum Zeitpunkt 12 Stunden nach Aufnahme. In der Gruppe der Patienten mit dekompensierter Herzinsuffizienz bzw. kardiogenem Schock im Rahmen eines akuten Myokardinfarktes dagegen fanden sich statistisch signifikant steigende NTproBNP-Werte zu allen Zeitpunkten innerhalb der ersten zwölf Stunden im Vergleich zum Aufnahmewert, wobei nach zwölf Stunden der Maximalwert erreicht wurde. Weiterhin zeigten in dieser Gruppe die NTproBNP-Werte eine statistische Signifikanz in Hinsicht auf die 18-Monatsmortalität zu fast allen Zeitpunkten außer 4 Stunden nach Aufnahme. Zusammenfassend kann somit mit Bestimmung der NTproBNP-Werte 12 Stunden nach Krankenhausaufnahme unabhängig von der Genese der akuten kardialen Dekompensation eine Kurz- und Langzeitprognoseabschätzung erfolgen.

No description available.

A computational and experimental study of the Richtmyer-Meshkov instability is presented here for an inclined interface perturbation. The computational work is composed of simulation studies of the inclined interface RMI performed using the Arbitrary Lagrange Eulerian (ALE) code called ARES. These simulations covered a wide range of Mach numbers (1.2 to 3.5), gas pairs (Atwood numbers 0.23to 0.95), inclination angles (30° to 85°), and explored various perturbation types (both inclined interface and sinusoidal). The computational work included the first parametric study of the inclined interface RMI. This study yielded the first scaling method for the inclined interface RMI mixing width growth rates. It was extended to explore the effect of perturbation linearity and identified that a sharp transition in growth regimes occurs for an initial perturbation inclination angle of 75° with angles below (above) this growing faster (slower). Finally a study of the effects of incident shock strength on the refracted shock wave perturbation decay rate is presented. This study examined how the perturbations induced on the transmitted shock front by the RMI decay with time and found that the decay rates follow a power law model, Alpha=Beta∗S^(Epsilon). When the coefficients from the power law decay model were plotted versus Mach number, a distinct transition region was found which is likely a result of the post-shock heavy gas velocity transitioning from the subsonic to supersonic range. The experimental portion of this work was conducted using the TAMUFMSTF, completed in May of 2012. This facility uses a variable inclination shock tube, with a modular construction design for incident shock strengths of up to Mach 3.0. It employs optical systems for measuring density and velocity fields simultaneously using the planar laser induced fluorescence and particle imaging velocimetry techniques. The design and construction of this facility is reviewed in detail in chapter 4 of this work. The initial experiments performed in the TAMUFMSTF provided the first known extensive experimental data for an inclined interface RMI. Planar laser Mie scattering images and velocity vectors were obtained for a N_(2)/CO_(2) interface at a 60° inclination angle and an incident shock strength of Mach 1.55. These images have been compared with simulations made using the ARES codes and have been shown to have some distinct differences. Some of these differences indicate that the initial conditions in the experiments deviate from the ideal planar interface. Other differences have revealed features which have not been resolved by the simulations due to resolution limitations.

Hsp22 has been implicated in stress tolerance and longevity in various organisms though its role in Drosophila melanogaster larval thermal tolerance has not yet been investigated. I undertook this project to determine if over-expression of hsp22 in either muscle or motor neurons could alter locomotor ability at high temperature in third instar larvae of D. melanogaster. A combination of the UAS-gal4 and tet-On promoter systems was used to over-express transgenic hsp22 in the larvae. A β-galactosidase assay was used to determine the level of gene expression following administration of different amounts of tetracycline. A concentration of 100 μg/ml of tetracycline was found to elicit appreciably higher expression of the reporter gene than 0 and 0.1 μg/ml of tetracycline. Locomotor ability of larvae was assessed at a temperature of approximately 400C by measuring the time to movement failure (TMF). Larvae that were fed 100 μg/ml of tetracycline showed a significant decline in the TMF, which could be attributed to the presence of tetracycline at a concentration of 100 μg/ml. Possible reasons behind the lack of a noticeable effect of hsp22 over-expression on the TMF are discussed. The detrimental effect of tetracycline could be attributed to the decline in mitochondrial translation or a decline in the population of endogenous bacteria, which are known to exert positive effects on the development and function of Drosophila larvae. / Thesis (Master, Biology) -- Queen's University, 2007-10-01 14:24:15.801

There is a thermal range for the operation of neural circuits beyond which nervous system function is compromised. Poikilotherms are particularly vulnerable to thermal stress, since their body temperature can fluctuate with ambient temperature. Animals that experience frequent hyperthermia have various coping mechanisms such as the thermoprotective effect of a prior exposure to sublethal temperatures (heat shock response). The molecular mechanisms of this thermoprotection have yet to be understood. This project studies the changes in protein expression in the nervous system of gregarious Locusta migratoria subjected to heat shock. For this purpose, proteins were extracted from metathoracic ganglia (MTG) by different methods and a proteomic map was subsequently obtained by 2-D gel electrophoresis which was compared between control (CON) and heat-shocked (HS) animals. Additionally, the localization pattern of Hsp70 was studied in the MTG of CON and HS gregarious locusts. Although 2-D gels showed changes in the amount of different isoforms of ATP-synthase β, the overall amount of this protein subunit was found to be unchanged. My experiments also revealed no significant change in the distribution of Hsp70 in the MTG of locusts caused by HS. However, new findings show that this protein is constitutively expressed at higher levels in perineurium, glia and tracheal cells than in neurons. In separate experiments, isolated locusts were also examined in order to measure any stress-associated increase of Hsp70 in the tissues of animals not previously exposed to crowding pressure. Quantitative western blots did not show a consistent change of the Hsp70 level in the MTG of isolated locusts following heat shock. Results of my research suggest that the change in the protein profile of the metathoracic ganglion following heat shock, if it exists, is subtle or occurs in very low-abundance proteins whose monitoring requires the application of special techniques. Alternatively, the thermoprotective effect of heat shock on the nervous system might be promoted through other pathways which can change the protein activity at the post-translational level and may work independently from protein synthesis. / Thesis (Master, Biology) -- Queen's University, 2009-03-20 12:28:32.962