Requirements for Staphylococcus aureus in vitro cellular internalization

Staphylcoccus aureus is a prokaryotic organism capable of causing numerous superficial and severe human infections. Adhesion of S. aureus to host tissues or cells is believed to be a crucial event in S. aureus infections. Subsequently, S. aureus can seed into the bloodstream resulting in metastasis of the infection. Several reports show that S. aureus can be internalized by non-professional phagocytes, a process which has been proposed to be important in S. aureus dissemination. An intracellular residence has also been proposed to provide safe harbor to reservoirs of dormant bacteria contributing to the persistence of infection. This dissertation describes an investigation into the molecular mechanisms of S. aureus internalization into both fibroblast and epithelial cells. Bacterial requirements for internalization were found to be limited to expression of proteins that bind the extracellular matrix protein fibronectin. A previously unknown fibronectin-binding region in the S. aureus fibronectin-binding protein A was discovered after showing competitive inhibition of S. aureus internalization. This novel fibronectin-binding activity is characterized. Internalization also required cell-based factors. The presence of fibronectin and cell surface receptors of the β1 integrin class, which are known to bind and internalize fibronectin, were found to be necessary for optimal internalization of S. aureus. These results led to the conclusion that fibronectin acts as a bridge between the bacterium and integrins on the host cells. The internalization process exhibits features characteristic of integrin-mediated cell migration on fibronectin-coated surfaces. Both processes involved an active form of the β1 integrin subunit and the protein tyrosine kinase Src. Finally, a Src inhibitor previously shown to be effective in reducing osteoporosis in an in vivo rat model is capable of greatly reducing S. aureus internalization. ^

The Optimal Capital Structure of Banks: Balancing Deposit Insurance, Capital Requirements and Tax-Advantaged Debt

The capital structure and regulation of financial intermediaries is an important topic for practitioners, regulators and academic researchers. In general, theory predicts that firms choose their capital structures by balancing the benefits of debt (e.g., tax and agency benefits) against its costs (e.g., bankruptcy costs). However, when traditional corporate finance models have been applied to insured financial institutions, the results have generally predicted corner solutions (all equity or all debt) to the capital structure problem. This paper studies the impact and interaction of deposit insurance, capital requirements and tax benefits on a bankÇs choice of optimal capital structure. Using a contingent claims model to value the firm and its associated claims, we find that there exists an interior optimal capital ratio in the presence of deposit insurance, taxes and a minimum fixed capital standard. Banks voluntarily choose to maintain capital in excess of the minimum required in order to balance the risks of insolvency (especially the loss of future tax benefits) against the benefits of additional debt. Because we derive a closed- form solution, our model provides useful insights on several current policy debates including revisions to the regulatory framework for GSEs, tax policy in general and the tax exemption for credit unions.

Identifying the roles of the Escherichia coli FtsZ-associated proteins by minimizing the requirements for division

Formation of the FtsZ ring (Z ring) in Escherichia coli is the first step in assembly of the divisome, a molecular machine composed of 14 known proteins which are all required for cell division. Although the biochemical functions of most divisome proteins are unknown, several of these have overlapping roles in ensuring that the Z ring assembles at the cytoplasmic membrane and is active. ^ We identified a single amino acid change in FtsA, R286W, renamed FtsA*, that completely bypasses the requirement for ZipA in cell division. This and other data suggest that FtsA* is a hyperactive form of FtsA that can replace the multiple functions normally assumed by ZipA, which include stabilization of Z rings, recruitment of downstream cell division proteins, and anchoring the Z ring to the membrane. This is the first example of complete functional replacement of an essential prokaryotic cell division protein by another. ^ Cells expressing ftsA* with a complete deletion of ftsK are viable and divide, although many of these ftsK null cells formed multiseptate chains, suggesting a role in cell separation for FtsK. In addition, strains expressing extra ftsAZ, ftsQ, ftsB, zipA or ftsN, were also able to survive and divide in the absence of ftsK. The cytoplasmic and transmembrane domains of FtsQ were sufficient to allow viability and septum formation to ftsK deleted strains. These findings suggest that FtsK is normally involved in stabilizing the divisome and shares functional overlap with other cell division proteins. ^ As well as permitting the removal of other divisome components, the presence of FtsA* in otherwise wild-type cells accelerated Z-ring assembly, which resulted in a significant decrease in the average length of cells. In support of its role in Z-ring stability, FtsA* suppressed the cell division inhibition caused by overexpressing FtsZ. FtsA* did not affect FtsZ turnover within the Z ring as measured by fluorescence recovery after photobleaching. Turnover of FtsA* in the ring was somewhat faster than wild-type FtsA. Yeast two-hybrid data suggest that FtsA* has an increased affinity for FtsZ relative to wild-type FtsA. These results indicate that FtsA* interacts with FtsZ more strongly, and its enhancement of Z ring assembly may explain why FtsA* can permit survival of cells lacking ZipA or FtsK.^

DISCHARGE PLANNING: A PROCESS MODEL

As the requirements for health care hospitalization have become more demanding, so has the discharge planning process become a more important part of the health services system. A thorough understanding of hospital discharge planning can, then, contribute to our understanding of the health services system. This study involved the development of a process model of discharge planning from hospitals. Model building involved the identification of factors used by discharge planners to develop aftercare plans, and the specification of the roles of these factors in the development of the discharge plan. The factors in the model were concatenated in 16 discrete decision sequences, each of which produced an aftercare plan.^ The sample for this study comprised 407 inpatients admitted to the M. D. Anderson Hospital and Tumor Institution at Houston, Texas, who were discharged to any site within Texas during a 15 day period. Allogeneic bone marrow donors were excluded from the sample. The factors considered in the development of discharge plans were recorded by discharge planners and were used to develop the model. Data analysis consisted of sorting the discharge plans using the plan development factors until for some combination and sequence of factors all patients were discharged to a single site. The arrangement of factors that led to that aftercare plan became a decision sequence in the model.^ The model constructs the same discharge plans as those developed by hospital staff for every patient in the study. Tests of the validity of the model should be extended to other patients at the MDAH, to other cancer hospitals, and to other inpatient services. Revisions of the model based on these tests should be of value in the management of discharge planning services and in the design and development of comprehensive community health services.^

Functional analysis of the sea urchin {\it orthodenticle\/} -related gene, {\it SPOTX\/}, in aboral ectoderm-specific gene activation and aboral ectoderm cell fate specification

An important question in developmental biology is how embryonic cell types are derived from a fertilized egg. To address this question, this thesis investigates the mechanisms by which the aboral ectoderm-specific Spec2a gene is spatially and temporally regulated during sea urchin embryogenesis. The Spec2a gene of the sea urchin Strongylocentratus purpuratus has served as a valuable maker to understand the basis of lineage-specific gene activation and the role of transcription factors in cell fate specification. The hypothesis is that transcription factors responsible for cell type-specific gene activation are key components in the initial cell specification step. The Spec2a gene, which encodes a small cytosolic calcium-binding protein, is expressed exclusively in aboral ectoderm cell lineages. The 1516-bp control region of the Spec2a gene contains a 188-bp enhancer element required for temporal activation and aboral ectoderm/mesenchyme cell expression, while an unidentified element upstream of the enhancer represses expression in mesenchyme cells. Using an enhancer activation assay, combined with site-directed mutagenesis, I showed that three TAATCC/T sites within the enhancer are responsible for enhancer activity. Mutagenizing these sites and a fourth one just upstream abolished all activity from the Spec2a control region. A 77-bp DNA fragment from the Spec2a enhancer containing two of the TAATCC/T sites is sufficient for aboral ectoderm/mesenchyme cell expression. A cDNA encoding SpOtx, an orthodenticle-related protein, was cloned from S. purpuratus and shown to bind with high affinity to the TAATCC/T sequences within the Spec2a control region. SpOtx transcripts were found initially in all cells of the cleaving embryo, but they gradually became restricted to oral ectoderm and endoderm cells, suggesting that SpOtx might play a role in the initial temporal activation of the Spec2a gene and most likely has additional functions in the developing embryo. To reveal the broader biological functions of SpOtx, I injected SpOtx mRNA into living sea urchin eggs to determine what effects overexpressing the SpOtx protein might have on embryo development. SpOtx mRNA-injected embryos displayed dramatic alterations in development. Instead of developing into pluteus larvae with 15 different cell types, uniform epithelia balls were formed. These balls consisted of a thin layer of squamous cells with short cilia highly reminiscent of aboral ectoderm. Immunohistochemical staining and RT-PCR demonstrated that the SpOtx-injected embryoids expressed aboral ectoderm markers uniformly, but showed very weak or no expression of markers for non-aboral ectoderm cell types. These data strongly suggested that overexpression of SpOtx redirected the normal fate of non-aboral ectoderm cells to that of aboral ectoderm. These results show that SpOtx is involved in aboral ectoderm differentiation by activating aboral ectoderm-specific genes and that modulating its expression can lead to changes in cell fate. ^

Seasonal and Rotational Influences on Corn Nitrogen Requirements

This project is designed to study the N fertilization needs in continuous corn (CC) and corn rotated with soybean (SC) as influenced by location and climate. Multiple rates of fertilizer N are spring applied, with the intent to measure yield response to N within each rotation on a yearly basis for multiple years at multiple sites across Iowa. This will allow the determination of N requirements for each rotation, differences that exist between the two rotations, responses to applied N across different soils and climatic conditions, and evaluation of tools used to adjust N application.

Water Table Level as Influenced by Rainfall, Crop Requirements, and Tiling Method during the past Three Years

In 1979, a portion of the research farm was pattern tiled including the large tillage plots. This was used as an opportunity to compare tile installation methods: a conventional trenching machine (used widely prior to late 70s), and a trenchless “tile plow” machine. The tile plow inserted plastic tile using a mole approach, which is the current primary tiling method. This research showed that plow and trenching tiling methods were not significantly different and both provided adequate drainage. It also showed that water table measurements were influenced more by timing of water needs of the crop being grown and intensity of the rainfall event than tiling method. This report focuses on continued research completed on these trial plots from 2009 to 2011 measuring water table level.

Seasonal and Rotational Influences on Corn Nitrogen Requirements

This project was designed to study the N fertilization needs in continuous corn (CC) and corn rotated with soybean (SC) as influenced by location and climate. Multiple rates of fertilizer N were spring applied, with the intent to measure yield response to N within each rotation on a yearly basis for multiple years at multiple sites across Iowa. This will allow the determination of N requirements for each rotation, differences that exist between the two rotations, responses to applied N across different soils and climatic conditions, and evaluation of tools used to adjust N application.

Seasonal and Rotational Influences on Corn Nitrogen Requirements

This project was designed to study the N fertilization needs in continuous corn (CC) and corn rotated with soybean (SC) as influenced by location and climate. Multiple rates of fertilizer N were spring applied, with the intent to measure yield response to N within each rotation on a yearly basis for multiple years at multiple sites across Iowa. This will allow determination of N requirements for each rotation, differences that exist between the two rotations, responses to applied N across different soils and climatic conditions, and evaluation of tools used to adjust N application.

Seasonal and Rotational Influences on Corn Nitrogen Requirements

This project was designed to study the N fertilization needs in continuous corn (CC) and corn rotated with soybean (SC) as influenced by location and climate. Multiple rates of fertilizer N were spring applied, with the intent to measure yield response to N within each rotation on a yearly basis for multiple years at multiple sites across Iowa. This will allow the determination of N requirements for each rotation, differences that exist between the two rotations, responses to applied N across different soils and climatic conditions, and evaluation of tools used to adjust N application.

Mineralogy and structural specification of ODP Leg 125 peridotite samples

Abundant serpentinite seamounts are found along the outer high of the Mariana forearc at the top of the inner slope of the trench. One of them, Conical Seamount, was drilled at Sites 778, 779, and 780 during Leg 125. The rocks recovered at Holes 779A and 780C, respectively, on the flanks and at the summit of the seamount, include moderately serpentinized depleted harzburgites and some dunites. These rocks exhibit evidence of resorption of the orthopyroxene, when present, and the local presence of very calcic-rich diopside in veins oblique to the main high-temperature foliation of the rock. The peridotites, initially well-foliated with locally poikiloblastic textures, show overprints of a two-stage deformation history: (1) a high-temperature (>1000°C), low-stress (0.02 GPa), homogeneous deformation that has led to the present Porphyroclastic textures displayed by the rocks and (2) heterogeneous ductile shearing at a much higher stress (0.05 GPa). This heterogeneous shearing probably describes a single tectonic event because it began at high temperatures, producing dynamic recrystallization of olivine in the shear zone, and ended at low temperatures in the stability field of chlorite and serpentine. In a few samples, olivine shows evidence of quasi-hydrostatic recrystallization at a very high temperature. Here, we propose that this recrystallization was related to fluid/magma percolation, a process that can also account for the resorption of the orthopyroxene and for the late crystallization of diopside veins in the rock. The impregnation by fluid or magma, development of the main high-temperature, low-stress deformation, and subsequent migration recrystallization of olivine probably occurred in a mantle fragment involved in the arc formation. In addition, this mantle has preserved structures that may have formed earlier in the oceanic lithosphere upon which the arc formed. Heterogeneous ductile shear zones in the peridotites may have developed during uplift. The "cold" deformation may have taken place during diapiric rise of hot mantle that underwent subsequent serpentinization or gliding along normal faults associated with the extension of the eastern margin of the forearc.

Las prescripciones curriculares y los procesos de programación de la enseñanza : Analizando algunas relaciones

El presente trabajo se enmarca en el Proyecto de Investigación denominado "Programación de la enseñanza en la escuela primaria: discursos y prácticas", aprobado en el Programa de Incentivos a la Investigación (H588). Nos interesa presentar en esta oportunidad un estado de avance de una línea de indagación que venimos desarrollando dentro del mencionado proyecto, referida a lo que en términos generales podríamos denominar las prescripciones curriculares. Es decir, nuestro interés está focalizado en analizar las prescripciones curriculares que se configuran y el carácter que a las mismas se les asigna en los diferentes niveles de concreción o especificación curricular. La programación de la enseñanza que estudiamos en nuestra investigación, entendida como un proceso progresivo de concreción de las intencionalidades educativas, puede ser analizada desde diferentes perspectivas. A los fines de esta presentación, priorizamos aquella que busca contextualizar las propuestas de clase de los maestros de la escuela primaria en el Diseño Curricular y en los Materiales de Desarrollo Curricular, prestándole atención a las prescripciones que se generan desde lo curricular y a la particular relectura que los docentes hacen de dichas prescripciones

Las prescripciones curriculares y los procesos de programación de la enseñanza : Analizando algunas relaciones

El presente trabajo se enmarca en el Proyecto de Investigación denominado "Programación de la enseñanza en la escuela primaria: discursos y prácticas", aprobado en el Programa de Incentivos a la Investigación (H588). Nos interesa presentar en esta oportunidad un estado de avance de una línea de indagación que venimos desarrollando dentro del mencionado proyecto, referida a lo que en términos generales podríamos denominar las prescripciones curriculares. Es decir, nuestro interés está focalizado en analizar las prescripciones curriculares que se configuran y el carácter que a las mismas se les asigna en los diferentes niveles de concreción o especificación curricular. La programación de la enseñanza que estudiamos en nuestra investigación, entendida como un proceso progresivo de concreción de las intencionalidades educativas, puede ser analizada desde diferentes perspectivas. A los fines de esta presentación, priorizamos aquella que busca contextualizar las propuestas de clase de los maestros de la escuela primaria en el Diseño Curricular y en los Materiales de Desarrollo Curricular, prestándole atención a las prescripciones que se generan desde lo curricular y a la particular relectura que los docentes hacen de dichas prescripciones

Las prescripciones curriculares y los procesos de programación de la enseñanza : Analizando algunas relaciones

El presente trabajo se enmarca en el Proyecto de Investigación denominado "Programación de la enseñanza en la escuela primaria: discursos y prácticas", aprobado en el Programa de Incentivos a la Investigación (H588). Nos interesa presentar en esta oportunidad un estado de avance de una línea de indagación que venimos desarrollando dentro del mencionado proyecto, referida a lo que en términos generales podríamos denominar las prescripciones curriculares. Es decir, nuestro interés está focalizado en analizar las prescripciones curriculares que se configuran y el carácter que a las mismas se les asigna en los diferentes niveles de concreción o especificación curricular. La programación de la enseñanza que estudiamos en nuestra investigación, entendida como un proceso progresivo de concreción de las intencionalidades educativas, puede ser analizada desde diferentes perspectivas. A los fines de esta presentación, priorizamos aquella que busca contextualizar las propuestas de clase de los maestros de la escuela primaria en el Diseño Curricular y en los Materiales de Desarrollo Curricular, prestándole atención a las prescripciones que se generan desde lo curricular y a la particular relectura que los docentes hacen de dichas prescripciones