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Advances In Nuclear Magnetic Resonance For Drug Discovery, Robert Powers

Robert Powers Publications

Background—Drug discovery is a complex and unpredictable endeavor with a high failure rate. Current trends in the pharmaceutical industry have exasperated these challenges and are contributing to the dramatic decline in productivity observed over the last decade. The industrialization of science by forcing the drug discovery process to adhere to assembly-line protocols is imposing unnecessary restrictions, such as short project time-lines. Recent advances in nuclear magnetic resonance are responding to these self-imposed limitations and are providing opportunities to increase the success rate of drug discovery.

Objective/Method—A review of recent advancements in NMR technology that have the potential of …

Stopping A Pandemic, Minnesota State University, Mankato

Health/Nutrition

Bibliography and photographs of a display of government documents from Minnesota State University, Mankato.

Effects Of Feeding Wet Distillers Grains Plus Solubles On Feedlot Manure Value, Virgil R. Bremer, Terry J. Klopfenstein, Galen E. Erickson, Richard K. Koelsch, Raymond E. Massey, Judson Vasconcelos

Nebraska Beef Cattle Reports

Feeding wet distillers grains plus solubles (WDGS) improves the fertilizer value and net value of feedlot manure for all feedlot sizes. The net fertilizer value of feedlot manure increased 375% to 550% since 2006. Valuing manure at 2008 fertilizer nutrient prices and feeding 20% or 40% WDGS instead of feeding a corn-based diet improved profitability by $7 to $17 per steer finished ($4 to $11 per ton of manure).

Comparison Of Dry Distillers Or Modified Wet Distillers Grains Plus Solubles In Wet Or Dry Forage Based Diets, Mallorie Willken, Terry L. Mader, Galen E. Erickson, Leslie J. Johnson

Nebraska Beef Cattle Reports

Modified wet distillers grains plus solubles (MDGS) or dry distiller grains plus solubles (DDGS) in combination with wet or dry forages were fed to growing steer calves (n =192). They were fed one of four treatments in a 2 x 2 factorial arrangement with factors as wet or dry forage and MDGS or DDGS for 105 days. Gain and feed-to-gain ratio (F:G) of steers fed MDGS were similar to those fed DDGS. Feeding wet forage significantly improved average daily gain (ADG) and F:G compared to feeding dry forage, which likely reflects forage quality in this study.

Cell Size Control And Asymmetric Cell Fates In Start Of The Saccharomyces Cerevisiae Cell Cycle, Talia, Stefano Di

Student Theses and Dissertations

Understanding the molecular and biophysical mechanisms that couple the process of cell growth to cell division is one of the major challenges of modern cell biology. Saccharomyces cerevisiae (budding yeast) has been an important model organism to study the coupling between cell growth and cell division. The insights obtained from studies of this unicellular organism have been pivotal for related studies in animal systems. The classical picture that emerged from studies in budding yeast was that cell cycle commitment in G1, at a point called Start, requires growth to a critical cell size. This deterministic model did not address how …

The Role Of Adult Stem Cells And Tumor Necrosis Factor In Peripheral Neuropathy, Prabhjot Singh Dhadialla

Student Theses and Dissertations

Peripheral neuropathies are a significant cause of morbidity and mortality, with a population prevalence of 2,400 per 100,000 (2.4%) that increases in the elderly to 8,000 per 100,000 (8%)(C. N. Martyn and R. A. Hughes, 1997). The variations in symptom distribution and etiologic attribution have resulted in the classification of over 100 types of peripheral neuropathy with specific patterns of development and prognoses. In the first study, we use a mouse model of hereditary peripheral neuropathy that results in hind-limb paralysis to investigate the therapeutic efficacy of adult, adipose derived stem cells (ADSC). The paralyzed mice that received ADSC transplantation …

Perceptual Learning Of Object Shape, Doruk Golcu

Student Theses and Dissertations

Recognition of objects is accomplished through the use of cues that depend on internal representations of familiar shapes. We used a paradigm of perceptual learning during visual search to explore what features human observers use to identify objects. Human subjects were trained to search for a target object embedded in an array of distractors, until their performance improved from chance levels to over 80% of trials in an object specific manner. We determined the role of specific object components in the recognition of the object as a whole by measuring the transfer of learning from the trained object to other …

Population Dynamics In A Model Closed Ecosystem, Doeke Romke Hekstra

Student Theses and Dissertations

For almost any species in any environment, it is nearly impossible to predict its fitness from molecular knowledge. If fitness is not to be a mere tautology, reproducible measurements of the survival and reproduction of populations are needed over many generations. Laboratory microbial ecosystems afford the short time and length scales required for such measurements. Their conventional implementations, batch cultures with period refreshment of growth medium or chemostats with continuous refreshment, have a number of disadvantages, such as the introduction of additional frequencies, selection for surface growth and the distortion of chemical interactions. In closed ecosystems free energy is instead …

Novel Roles For The Tissue Plasminogen Activator System In The Development Of Fetal Alcohol Syndrome And The Regulation Of Contextual Learning After Stress, Melissa Noel-Castro

Student Theses and Dissertations

Ethanol exposure during synaptogenesis can result in brain and behavior neurotoxic defects referred to as fetal alcohol syndrome (FAS). Since tissue plasminogen activator (tPA) has been implicated in mediating excitotoxic neurodegeneration we subjected neonatal WT and tPA^-/- to an acute ethanol paradigm that serves as a model of FAS. We observed persistent upregulation of tPA and extensive neurodegeneration after ethanol in the forebrain of WT. However, tPA^-/- mice were protected from neuronal death, suggesting tPA mediates ethanol-induced neurodegeneration and FAS in mice. Commensurate with neuronal death, we observed ethanol-induced cognitive impairments in adult WT, but not tPA^{-/- …}

Mechanistic And Physiological Studies Of The Insulin-Dependent Regulation Of Foxa2, Jessica Jean Howell

Student Theses and Dissertations

The Forkhead box A2 transcription factor (Foxa2/HNF-3β) has been shown to be a key regulator of genes involved in the maintenance of glucose and lipid homeostasis in the liver, and is constitutively inactivated in several hyperinsulinemic/obese mouse models, thereby enhancing their metabolic phenotypes. Foxa2 is activated under fasting conditions, but is inhibited by insulin signaling via PI3K/Akt in a phosphorylation-dependent manner, which results in its nuclear exclusion. However, the mechanism and relative importance of nuclear export have not yet been elucidated. In addition, the existence and potential role of insulin-dependent regulation of Foxa2 have not been studied in other tissues …

The Neural Circuitry Of Social Behavior In C. Elegans, Evan Z. Macosko

Student Theses and Dissertations

Most animal species, from simple invertebrates to complex mammals, require behavioral mechanisms to communicate with and respond to conspecifics, whether to mate, to assess predatory danger, or evaluate the nutritional quality of the surrounding environment. Understanding the molecular and cellular underpinnings of these social behaviors remains a central challenge in neurobiology. I used the nematode C. elegans as a model system to study the genetics and neural circuitry that underlie social behavior. First, I evaluated the behavioral responses of C. elegans to a nematode extract (deathmone), which served as a model for alarm pheromones in other animal species (chapter 2). …

Fibrin Formation And Dissolution In The Progression Of Amyloid-Beta Pathology In Alzheimer's Disease, Justin Paul

Student Theses and Dissertations

Alzheimer's disease (AD) is a neurodegenerative disorder that leads to profound cognitive decline and eventually death. There are no effective long-term treatments or preventative measures available, and as the incidence and prevalence of the disease are increasing, new insights and tractable therapeutic targets are sorely needed. Genetic evidence indicates that a major cause of AD is the production of the amyloid-β (Aβ) peptide, which is proteolytically derived from the amyloid-β precursor protein. The Aβ peptide can oligomerize and be deposited as extracellular plaques in the brain and blood vessels, but the mechanism of how it leads to neuronal death is …

Novel Interactions Of The Hormone Leptin Revealed By Pet Imaging In Rodents And Rhesus Macaques, Robert Richard Flavell

Student Theses and Dissertations

Leptin is a polypeptide hormone, secreted principally by adipose tissue, which functions as an afferent signal in a feedback loop to maintain body weight and energy homeostasis. In addition to its well documented effects on food intake and energy expenditure, leptin modulates the function of many other physiological systems in mammals, through actions in the central nervous system and periphery. Remarkably, despite extensive studies on leptin receptor expression, the physiological biodistribution of the hormone remains essentially unknown. In order to characterize the distribution leptin in mammals, we have developed methodologies to radiolabel the hormone and visualize its biodistribution using positron …

Glia Are Required For Sensory Neuron Morphology And Function In Caenorhabditis Elegans, Taulant Bacaj

Student Theses and Dissertations

The nervous system emerges from the coordinated development of neurons and glia. To better understand the processes that enable nervous system development and function we have studied the sensory organs of Caenorhabditis elegans because their anatomy and function are well-characterized. Specifically, we have focused on two aspects of sensory organs: how do glia interact with neurons to enable proper development and function and how are sensory cilia generated. To uncover any glial roles, we ablated the major glial cell of the amphid sensilla. Embryonic glial ablation did not affect neuronal survival and resulted in sensory neuron dendrites that were far …

Specification And Function Of Early Hair Follicle Stem Cells, Jonathan Nowak

Student Theses and Dissertations

In adult skin, multipotent epithelial stem cells (SCs) reside in a quiescent niche associated with each hair follicle termed the "bulge" and are essential for cyclic bouts of hair growth. Bulge stem cells can also contribute to sebaceous glands and the intefollicular epidermis when it is injured. While hair follicles begin to develop during embryogenesis, niche architecture becomes pronounced postnatally at the start of the first hair cycle. Whether SCs exist or function earlier is unknown. To determine if a stem cell population exists during follicle development, I conducted embryonic pulse-chase experiments to identify putative stem cells based on slow-cycling …

Regulation Of Apoptosis By Xiap Ubiquitin- Ligase Activity, Andrew James Schile

Student Theses and Dissertations

Virtually all animal cells have the known ability to self-destruct by undergoing apoptosis, a morphologically distinct form of programmed cell death. The proper regulation of apoptosis is critical for both development and tissue homeostasis, and inhibition of apoptosis contributes to the development and progression of cancer. Inhibitor of Apoptosis Proteins (IAPs) can bind to and inhibit caspases, the key executioners of apoptosis. Because IAPs are frequently over-expressed in human tumors, they have become major pharmacological targets for developing new cancer therapeutics. Many IAPs contain RING domains that function as E3 ubiquitin-ligases to regulate the abundance of IAPs themselves and their …

The Manipulation Of Apical Dendritic Plasticity And The Consequences For The Effects Of Chronic Stress, Trudy Mccall

Student Theses and Dissertations

Pyramidal cell apical dendrites in region CA3 of the hippocampus of male rats collapse in size and complexity following chronic stress. These dendrites return to control sizes with a recovery period. This suggests that dendritic remodeling can function as a protective response mechanism, protecting the region from exposure to the increased amounts of excitatory amino acid released in stress. If this is the case, then a situation in which remodeling is prevented during stress should be more damaging to the long-term survival of the organism. To examine this, animals were treated with endo N, an enzyme that cleaves PSA from …

Perceptual Learning, Long-Range Horizontal Connections And Top-Down Influences In Primary Visual Cortex, Valentin Piëch

Student Theses and Dissertations

The earliest cortical stage of visual processing, the primary visual cortex, has long been seen as a static preprocessor that finds local edges and their orientation like a linear filter bank, and passes this information on to downstream visual areas. This view has been challenged in recent years since the discovery of contextual influences, that is, interactions between the responses of neurons that encode for non-overlapping adjacent areas of visual space, and their anatomical substrate, long-range horizontal connections. These contextual interactions have been shown in awake behaving primates to be modulated depending on the task the animals are performing. A …

Peak Mitotic Cyclin Permits Mitotic Exit, Benjamin Drapkin

Student Theses and Dissertations

In eukaryotes, DNA replication, mitosis, and cytokinesis are all regulated by Cyclin-dependent kinase (Cdk). Cyclin/Cdk complexes promote replication origin firing and mitotic entry, and conversely, inhibit pre-replication origin loading and exit from mitosis. Cyclin synthesis and degradation, Cdk phosphorylation and Cdk inhibitors are controlled such that Cdk activity oscillates once per cell cycle. Little is known about the quantitative relationship between the level of Cdk activity and the occurrence, rate, and coordination of cell cycle events. We have addressed this question in Saccharomyces cerevisiae by introducing titrated levels of undegradable mitotic B-cyclin (Clb2kd) in cells prior to release of a …

Transcriptional Regulation Of Adipocyte Function, Kivanç Birsoy

Student Theses and Dissertations

The increased white adipose tissue mass associated with obesity is the result of both hyperplasia and hypertrophy of adipocytes. While adipocyte development and transcriptional processes are well studied in vitro, regulation of in vivo genes (such as leptin), the identity of the adipocyte progenitor cells and the development of the adipose organ have not been defined invivo. In this thesis, firstly KLF4 was discovered to be an essential early regulator of adipogenesis. KLF4 together with Krox20 cooperatively transactivates C/EBPβ, suggesting that KLF4 and Krox20 are part of an immediate early transcriptional network. This network is upregulated in a lipodystrophic animal …

Transfer Properties Of The Hair Cell-Afferent Fiber Synapse, Erica C. Keen

Student Theses and Dissertations

The perception of sound is initiated in the inner ear by the conversion of vibrational energy into a neural code, a transduction process achieved by the chemical synapses of hair cells in the auditory periphery. Thus, the operation of the hair cell's presynaptic active zone is key to understanding auditory transduction. However, the lack of suitable experimental systems in which to investigate both the presynaptic and postsynaptic aspects of this synapse with high resolution has limited our understanding of its functional characteristics. This work describes the development of a novel in vitro preparation of the amphibian papilla from Rana catesbeiana …

Regulation Of Immunoglobulin Gene Diversification By Noncoding Rna's, Grace Teng

Student Theses and Dissertations

Small regulatory RNAs supplement the canonical pathways of gene regulation through diverse mechanisms of transcriptional, post-transcriptional, and post-translational silencing. These mechanisms range from "classical" RNA interference (RNAi), to gene repression by microRNAs (miRNAs), to maintenance of genomic stability by repeatassociated small RNAs. Here, I describe the contribution of miRNA-mediated regulation to a specific case of gene expression that requires significant somatic alteration of the genetic code. B lymphocytes perform somatic hypermutation (SHM) and class switch recombination (CSR) of the immunoglobulin locus to generate an antibody repertoire diverse in both affinity and function. These somatic diversification processes are catalyzed by activation-induced …

Regulation Of Gene Expression In Trypanosoma Brucei, Tim Nicolai Siegel

Student Theses and Dissertations

The protozoan parasite Trypanosoma brucei is one of the most divergent well-studied eukaryotes and many discoveries of general interest have been made in T. brucei. Atypical for a eukaryote, in T. brucei genes transcribed by RNA polymerase II (RNA pol II) are arranged in polycistronic transcription units (PTUs). mRNAs are separated post-transcriptionally by coupled splicing and polyadenylation reactions. During the splicing reaction a 39 nt 'sliced-leader' is added to every mRNA, a process termed trans splicing. The arrangement of generally unrelated genes in PTUs has lead to the assumption that little gene regulation occurs at the level of transcription initiation …

Physiological Effects Of Estradiol In The Mouse Hippocampal Formation, Joanna L. Spencer

Student Theses and Dissertations

At several points in a woman's life, changes in circulating estradiol are associated with disturbances in mood and cognitive function. To determine the biological basis of these behavioral changes, researchers have concentrated on the hippocampal formation, a medial temporal lobe structure involved in the regulation of mood and cognition in humans. It is now clear that estradiol increases the substrates of hippocampal synaptic plasticity, including dendritic spine density, synapse density, and synaptic protein expression. In some cases, these changes are associated with alterations in mood and hippocampal-dependent learning and memory. The upstream mediators of these estradiol effects remain unknown, but …

Synaptic Protein Profiling In The Mammalian Brain, Elizabeth Heller

Student Theses and Dissertations

The mammalian central nervous system (CNS) contains billions of neurons each receiving thousands of synaptic inputs. Synapses are specified in part through the precise localization of synaptic proteins, yet it has not previously been possible to analyze the protein content of an individual class of synapses. In order to achieve this, we have used the BAC (bacterial artificial chromosome) transgenic approach to target particular neurons for expression of a given neurotransmitter receptor fused to an affinity tag. Immunohistochemistry of fixed brain tissue confirmed the correct localization of each synaptic fusion protein to the appropriate cell type and morphological structure. In …

Dissecting The Development And Function Of C. Elegans Glia With Mutations Of The Mls-2 And Vab-3 Genes, Yoshimura Satoshi

Student Theses and Dissertations

The past decade has produced much evidence that glia, the major cellular component of vertebrate nervous systems, play active integral roles in a variety of processes including neuronal migration, synaptogenesis, and modulation of synaptic activity. Yet, many aspects of glia-neuron interactions remain obscure partly because manipulation of glia can result in neuronal death, hampering attempts to study glial cells in vivo. Moreover, a comprehensive understanding of glia differentiation is not yet achieved, although several key molecules in the process have been discovered. C. elegans possesses glia-like cells that are morphologically reminiscent of vertebrate glia. In this thesis, I show that …

A Model Of The Production Of Spontaneous Otoacoustic Emissions In The Tokay Gecko, Michael Gelfand

Student Theses and Dissertations

The role of the ear is to detect sound. Many ears, however, can also generate sounds and transmit them into the environment. These sounds, known as spontaneous otoacoustic emissions, are the most striking proof of the existence of an active process within the ear. This active process originates in hair cells, the sensory receptors of the inner ear; by augmenting the energy contained in sound, it improves both the sensitivity and the frequency selectivity of hearing. Under certain conditions, the active process generates spontaneous oscillations, which then produce spontaneous emissions. Little is known about the process by which the spontaneous …

An In Vivo Characterization Of The Functional Role Of Two Novel Genes: Stard5 And Adam11, Marc Paul Waase

Student Theses and Dissertations

Regulation of cholesterol levels within cells and organisms is crucial for their survival. Maintenance of cellular cholesterol homeostasis occurs mainly at the transcriptional level, via the Sterol Regulatory Element Binding Proteins (SREBP), the Liver X Receptors (LXR), and the Unfolded Protein Response (UPR)/ER Stress Response. This thesis attempts to characterize the in vivo physiological role of novel downstream target genes of these transcription factors: StARD5 and ADAM11. This thesis outlines the development and characterization of a floxed mouse allele of the UPR-upregulated, reticuloendothelial gene StARD5, as well as two different transgenic mouse lines, one which expresses the human StARD5 gene …

Biochemical And Genetic Studies Of Beclin 1 Function In Autophagy, Yun Zhong

Student Theses and Dissertations

Beclin 1 is a mammalian autophagy protein and has important functions in development, tumor suppression and neurodegeneration. Beclin 1 exists in a protein complex with Vps34, which is a class III phosphatidylinositol (PtdIns) 3-kinase and mediates multiple vesicle trafficking pathways including autophagy and endocytosis. However the precise role of Beclin 1 in autophagy regulation is not well understood and information is lacking regarding the function of Beclin 1 in neuronal development and degeneration. In a study that combines mouse genetics and biochemistry, three novel Beclin 1 interaction proteins Atg14L (yeast Atg14-like), Rubicon (RUN domain and cysteine-rich domain containing, Beclin 1-interacting …

Circuit Dynamics Of Adult Visual Cortex, Homare Yamahachi

Student Theses and Dissertations

Learning and other forms of plasticity result from changes in transmission at existing synapses or the construction or elimination of synapses. Synapses occur at the juxtaposition of boutons, with their postsynaptic partners, dendrites and cell bodies. It has been assumed that connections in the primary visual cortex (V1) become static after the critical period. Recent studies show, however, that dendritic spines appear and disappear during adulthood in the normal brain. Our first objective was then to determine whether axonal branches and boutons also undergo morphological changes. To do so, we performed longitudinal studies of virally labeled neurons and their processes. …