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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
831

A case study research of asymmetrical relationshipsbetween service providers and emerging companieswithin the healthcare industry

Possnert, Oliver, Schön, Adam January 2018 (has links)
This master thesis report aims to highlight the importance ofinterorganizational relationships between experienced serviceproviders and emerging biopharmaceutical (EBP) companies within theSwedish healthcare industry. A shift in innovation strategiesregarding new pharmaceutical- and medical device products hasprompted a paradigm shift within a complex industry wherecollaborations between organisations has become increasinglycrucial. With a better understanding of how these companiesoperates, increased collaboration efforts could result in a fasterand more precise product development with new products reaching themarket improving the health for people around the world. In order toallow experienced service providers to enhance services towards EBPcompanies, a fundamental understanding of how decision makers withinthese EBP companies prefer to conduct relationships is needed. Wehave examined relationship preferences of EBP companies byconducting a qualitative case study through 14 interviews withdecision makers combined with a quantitative conjoint analysis.Eight factors was identified as important for when EBP companiesdecide to engage with a service provider: cost behavior,professional competence, adaptability, communication, personalrelationship, stability, EBP insight and size. The factorsadaptability, personal relationship, cost and size were used in theconjoint analysis to determine their relative importance which showthat adaptability and cost behavior was of the largest importance.With descriptions of each factor, we have provided a meaningfulguide to action of how to address these factors as a serviceprovider. The relationships is largely investigated as relationshipsbetween contract research organizations (as service providers) andEBP companies, but we have created a framework applicable forservice providers within the healthcare industry in general.
832

The Effect of Energy Drinks on Cardiovascular Variables: A Randomized Controlled Trial

Lee, Cynthia 01 January 2019 (has links)
Many studies have investigated the effects of energy drinks on cardiovascular parameters. These studies were typically conducted with high volume (32 ounces) energy drinks and have demonstrated association with QT prolongation and blood pressure elevation after consumption. Currently, there is inconclusive evidence with lower volume energy drinks. This study intends to evaluate the effects of the largest commercially available energy drink can (24 ounces) in the United States on cardiovascular parameters compared with placebo arm. A randomized, double-blinded, placebo-controlled, crossover trial was conducted over 2 separate days with a minimum of 6-day wash out period. Healthy volunteers between the age of 18 and 40 randomly consumed either a 24 oz energy drink or 24 oz placebo control drink on different days. Subjects were required to fast overnight and refrain from products containing caffeine or alcohol 48 hours prior to each study day. ECG, peripheral and central BP, heart rate, and augmentation index were measured at baseline, 1, 2, 3, and 4 hours post-consumption. Primary endpoints were average maximum change of corrected QT (QTc) interval and peripheral systolic blood pressure (pSBP) from baseline. The study enrolled 20 participants with a mean age of 23±5 years. The maximum baseline-adjusted difference of QTc interval was significantly higher in the energy drink arm than the placebo arm (13.68 ± 12.71 vs 4.20 ± 8.80 ms, respectively, p = 0.007). The maximum baseline-adjusted difference of pSBP was significantly higher in the energy drink arm compared to placebo (11.10 ± 5.24 vs 6.08 ± 7.07 mmHg, respectively; p= 0.006). Maximum baseline-adjusted difference of central diastolic BP and systolic and diastolic BP were also statistically significantly higher in the energy drink arm. This study demonstrated that a single, 24-ounce can of an energy drink can significantly prolong the QTc interval and raise pSBP.
833

Bulldog in Blue and Gold

Brown, Stacy D. 01 April 2017 (has links)
No description available.
834

I Liked That Song Before It Was Popular

Brown, Stacy D. 01 July 2014 (has links)
No description available.
835

Random Mutagenesis of the Aspergillus Oryzae Genome Results in Fungal Antibacterial Activity

Leonard, Cory A., Brown, Stacy D., Hayman, James Russell 09 July 2013 (has links)
Multidrug-resistant bacteria cause severe infections in hospitals and communities. Development of new drugs to combat resistant microorganisms is needed. Natural products of microbial origin are the source of most currently available antibiotics. We hypothesized that random mutagenesis of Aspergillus oryzae would result in secretion of antibacterial compounds. To address this hypothesis, we developed a screen to identify individual A. oryzae mutants that inhibit the growth of Methicillin-resistant Staphylococcus aureus (MRSA) in vitro. To randomly generate A. oryzae mutant strains, spores were treated with ethyl methanesulfonate (EMS). Over 3000 EMS-treated A. oryzae cultures were tested in the screen, and one isolate, CAL220, exhibited altered morphology and antibacterial activity. Culture supernatant from this isolate showed antibacterial activity against Methicillin-sensitive Staphylococcus aureus, MRSA, and Pseudomonas aeruginosa, but not Klebsiella pneumonia or Proteus vulgaris. The results of this study support our hypothesis and suggest that the screen used is sufficient and appropriate to detect secreted antibacterial fungal compounds resulting from mutagenesis of A. oryzae. Because the genome of A. oryzae has been sequenced and systems are available for genetic transformation of this organism, targeted as well as random mutations may be introduced to facilitate the discovery of novel antibacterial compounds using this system.
836

Stability of Ampicillin in Normal Saline Following Refrigerated Storage and 24-Hour Pump Recirculation

Huskey, Mariah, Lewis, Paul O., Brown, Stacy 10 December 2019 (has links)
Purpose: Use of ampicillin in outpatient parenteral antimicrobial therapy (OPAT) has historically been complicated by frequent dosing and short beyond use dates. However historic stability data relied on inaccurate testing methods. The purpose of this study is to evaluate the stability of ampicillin using high-pressure liquid chromatography (HPLC), the gold standard, in a real-world OPAT dosing model using continuous infusion at room temperature over 24 hours immediately following preparation compared to batches stored under refrigeration for 24 hours, 72 hours, and 7 days. Methods: An HPLC method was developed and validated as stability – indicating according to guidance in USP general Chapter < 1225 >. Method development included linearity, precision, accuracy, repeatability and forced degradation. Four batches were prepared using 4 different lots from 2 different manufacturers for each storage condition (immediate, 24 hours, 72 hours, and 7 days). Three 2-gram vials were each reconstituted with 10 mL of sterile water for injection (SWFI) and added to 250 mL of normal saline by a licensed pharmacist and stored in a laboratory refrigerator (2 – 8oC). A pump system was used to continuously circulate the solutions through medical grade tubing at room temperature. One milliliter aliquots were removed from each batch at time 0, 4 hours, 8 hours, 12 hours and 24 hours and analyzed for ampicillin concentration using the aforementioned HPLC method. The samples were filtered prior to analysis using a 0.22-micron syringe filter and analyzed in triplicates along with freshly prepared calibration samples (24 – 12 mg/mL). Peak area was used to determine percent recovery for each sample. Results:Each batch was assayed for initial concentration (20.34 – 21.50 mg/mL) upon preparation, and percent recovery was compared to that initial concentration thereafter. Acceptable recovery was defined as 90 – 110% of initial concentration. On the day of product preparation (immediate use), the average percent recovery over 24 hours was 96.4%. The other average percent recoveries were as follows: 95.8% (24-hour storage), 94.6% (72-hour storage) and 90.3% (7-day storage). These data represent the average percent recovery for all time points during the 24 hours sampling (n = 60 for each experiment). When evaluating individual time points, the percent recovery remained above 90% for all batches and time points except for the 7-day storage experiment. Under 7-day storage conditions, the percent recovery fell below 90% after 4 hours of circulation through the medical grade tubing. Furthermore, 95% confidence interval for percent recovery for ampicillin in the samples stayed within 90 – 110% of the initial concentration for the duration of the experiment for all test groups except 7-day storage. Conclusion:Ampicillin can be prepared and stored in a refrigerator for up to 72-hours prior to continuously infusing at room temperature over 24 hours with less than a 10% loss of potency over the dosing period. This model supports twice weekly OPAT delivery of ampicillin.
837

Phospholipid Depletion Techniques in LC-MS Bioanalysis

Brown, Stacy D., Carmichael, J. 01 March 2019 (has links)
Revised and Expanded Handbook Provides Comprehensive Introduction and Complete Instruction for Sample Preparation in Vital Category of Bioanalysis Following in the footsteps of the previously published Handbook of LC-MS Bioanalysis, this book is a thorough and timely guide to all important sample preparation techniques used for quantitative Liquid Chromatography–Mass Spectrometry (LC-MS) bioanalysis of small and large molecules. LC-MS bioanalysis is a key element of pharmaceutical research and development, post-approval therapeutic drug monitoring, and many other studies used in human healthcare. While advances are continually being made in key aspects of LC-MS bioanalysis such as sensitivity and throughput, the value of research/study mentioned above is still heavily dependent on the availability of high-quality data, for which sample preparation plays the critical role. Thus, this text provides researchers in industry, academia, and regulatory agencies with detailed sample preparation techniques and step-by-step protocols on proper extraction of various analyte(s) of interest from biological samples for LC-MS quantification, in accordance with current health authority regulations and industry best practices. The three sections of the book with a total of 26 chapters cover topics that include: Current basic sample preparation techniques (e.g., protein precipitation, liquid-liquid extraction, solid-phase extraction, salting-out assisted liquid-liquid extraction, ultracentrifugation and ultrafiltration, microsampling, sample extraction via electromembranes) Sample preparation techniques for uncommon biological matrices (e.g., tissues, hair, skin, nails, bones, mononuclear cells, cerebrospinal fluid, aqueous humor) Crucial aspects of LC-MS bioanalytical method development (e.g., pre-analytical considerations, derivation strategies, stability, non-specific binding) in addition to sample preparation techniques for challenging molecules (e.g., lipids, peptides, proteins, oligonucleotides, antibody-drug conjugates) Sample Preparation in LC-MS Bioanalysis will prove a practical and highly valuable addition to the reference shelves of scientists and related professionals in a variety of fields, including pharmaceutical and biomedical research, mass spectrometry, and analytical chemistry, as well as practitioners in clinical pharmacology, toxicology, and therapeutic drug monitoring.
838

The potency of AG10 in stabilizing transthyretin is driven by interactions mimicking the disease-suppressing T119M variant

Liang, Dengpan 01 January 2019 (has links)
Transthyretin (TTR) amyloid cardiomyopathy (ATTR-CM) is a fatal disease with no available disease-modifying therapies. While destabilizing TTR mutations increase the risk of developing ATTR-CM, the naturally occurring Thr119Met (T119M) variant stabilizes TTR and prevent disease. The two Serine 117 and Serine 117’ (S117/S117’) side chain hydroxyl groups of monomers A and B in T119M variant TTR form direct hydrogen bonds with each other. AG10 is an orally available, small molecule TTR stabilizer in Phase 3 clinical development for ATTR-CM. Structural features that infer high potency of AG10 for stabilizing TTR remains incompletely characterized. In order to investigate the contribution of hydrogen bonds between the pyrazole ring of AG10 and the two S117/S117’ and the salt bridges between carboxyl group and two Lysine 15 and Lysine 15’ (K15/K15’) on the stabilization of TTR, we synthesized three AG10 analogues (compounds 1, 2, and 3). Isothermal titration calorimetry (ITC) was used to determine the binding affinities (Kd) of ligands to TTR. Biochemical studies were used to compare the potency of AG10 relative to other ligands in stabilizing TTR in buffer and human serum. Results highlight the crucial roles played by the carboxyl group and pyrazole ring of AG10 and the importance of the hydrogen bonds it forms with the two TTR dimers, mimicking the interactions in the protective T119M-TTR mutation and enhancing the kinetic stability of the TTR tetramer.
839

Developing a Rational Peptide Ligand Design Method Using CD13 as a Prototype Target Receptor

Uddin, Md Zahir 01 January 2019 (has links)
Structure based computational peptide design methods have gained significant interest in recent years with the availability of structural insights of protein-protein interactions obtained from the crystal structures. Most of these approaches design new peptide ligands by connecting the crucial amino acid residues from the protein interface and are generally not based on any predicted receptor-ligand interaction. In this work, a peptide design method based on the Knob-Socket model was used to identify the specific ligand residues packing into the receptor interface. This method enables rational peptide ligand design by predicting amino acid residues that will fit best at the binding site of the receptor protein. Specific peptide ligands for the model receptor CD13 that are overexpressed in several cancer types were designed in this study. From the initial library of designed peptides, three potential candidates were selected based on simulated energies in the CD13 binding site using the programs Molecular Operating Environment (MOE) and AutoDock Vina. In the CD13 enzymatic activity inhibition assay, the three identified peptides exhibited 2.7 to 7.4 times lower IC50 values (GYPAY, 227 µM; GFPAY, 463 µM; GYPAVYLF, 170 µM) when compared to the known peptide ligand CNGRC(C1-C5) (1260 µM). The binding affinities of the peptides (GYPAY, Ki = 54.0 µM; GFPAY, Ki = 74.3 µM; GYPAVYLF, Ki = 38.8 µM) were 10 to 20 times higher than that of CNGRC (C1-C5) (Ki = 773 µM). The double reciprocal plots from the steady state enzyme kinetic assays confirmed the binding of the peptides to the intended active site of CD13. The cell binding and confocal microscopy assays showed that the designed peptides selectively bind to the CD13 on cell surface. The designed peptide-drug conjugates (PDCs) showed lower in vitro cytotoxicity and slightly better in vivo antitumor efficacy as compared to a model drug MMAE. However, the PDCs contributed to much lower weight loss in mice indicating lower side effects in vivo. This study demonstrated the feasibility of a Knob-Socket based rational design of novel peptides ligands in improving the identification of specific binding in comparison to the labor intensive current methods.
840

Evaluation of Human Stem Cell-Derived Neurons in 2D and 3D Cultures for Neurodevelopmental Studies, Epilepsy Disease Modeling and Drug Discovery

Salmanzadeh-Dozdabi, Hamed 01 January 2023 (has links) (PDF)
Human stem cells have revolutionized the study of early neural development, offering a powerful tool to investigate the complex processes involved in the formation of the nervous system. In this study, the human pluripotent stem cell line, TERA2.cl.SP12, was utilized to derive neuroglial cells and to determine their differentiation and functional maturation up to one year in culture; this model was then investigated as a new tool for the study of neurodevelopmental toxicity, for seizure modeling and as a screening method for the investigation of new anticonvulsants. Immunocytochemistry experiments determined that non-differentiated cells expressed the stem cell marker Oct-3/4 and, when exposed to retinoic acid, differentiated into neurons that expressed the neural marker proteins, β-III tubulin, MAP2 and the glial cells expressed GFAP. Immunoblotting analysis of the neural protein βIII-tubulin expression revealed robust expression from 2 months to 12 months of culture, indicating that the neurons remained viable and stable for an extended period. GFAP expression significantly increased at 4 and 8 months of culture, indicating that gliogenesis followed neurogenesis in vitro. These findings support the concept that the neural differentiation of human embryonal carcinoma (EC) stem cells follows a developmental program that closely mimics the intrinsic timescale observed in vivo, as has been observed in human ES and iPS cells.Multi-electrode array (MEA) studies indicated that these neuroglia cultures display complex electrochemical signaling including high frequency trains of action potentials from single neurons, neural network bursts and highly synchronized firing patterns which all increased significantly over one year in culture and indicated complex network formation and neural maturation. Neural activity in this 2D neuron-glia culture was modulated by a variety of voltage-gated and ligand-gated ion channel acting drugs and indicated the presence of inhibitory and excitatory synapses and integrated neural circuits. To test these stem cell derived neurons as a model for epilepsy disease modeling and drug screening, epileptiform activity was induced by the proconvulsant agent 4-aminopyridine (4-AP) in the neural circuits and five antiseizure drugs, representing a diverse group of clinically important agents for epilepsy, were examined. MEA data showed that 4-AP evoked epileptiform-like activity and increased spike frequency, single cell burst firing, and synchronized network bursting in the neuroglial cultures. In addition, spontaneous neural network activity and 4-AP-evoked epileptiform activity were inhibited by first, second and third generation antiseizure agents, consistent with animal and human studies. Pluripotent stem cell-based systems have proven useful in the study of developmental neurotoxicity. Here the impact of 2 widely used anti-epileptic drugs (AEDs), topiramate and gabapentin, on neural development was determined using TERA2.cl.SP-12 stem cell neurons. Transient exposure to gabapentin (3-300µM) or topiramate (3-300µM) did not affect cell viability, proliferation, or differentiation after a 30-day exposure period, except at concentrations of topiramate above the therapeutic range, and which led to a significant reduction in neural differentiation. The impact of chronic exposure to topiramate and on functional activity of neurons was then determined over ultra-long-term cell cultures. Results showed that topiramate decreased firing rate and synchrony index at a concentration of 30µM compared to control. Notably, these effects did not appear until 36 to 52 weeks, implying ‘silent neurotoxicity’ of developmental processes and functional deficits that do not surface until much later. These findings also suggest that human pluripotent stem cells and their neuronal derivatives can advance toxicological research by reducing the time and costs involved, whilst also minimizing the need for animal testing. Brain organoids offer a highly advanced model for the study of early embryonic and fetal brain development as well as human-specific disorders. In the next phase of this study, TERA2.cl.SP-12 stem cells were differentiated into 3D culture (neural organoids) by utilizing Stemcell Technologies STEMdiff cerebral organoid protocol. After 100 days differentiation, immunolabeling of the neural marker protein (βIII-tubulin) and glial cells (GFAP) revealed strong expression and presence of neuroglial cells differentiated from stem cells in the organoid cultures. Interestingly, immunocytochemistry labeling showed GFAP-positive cells surrounding ventricular-like zone (VZ) areas, suggesting VZ formation in the organoids. Multi-electrode array recordings demonstrated spontaneous spiking, single cell bursts and synchronized which all increased significantly over 30 weeks of differentiation. Neural activity in the organoids was modulated by a variety of voltage-gated and ligand-gated ion channel acting drugs and revealed the presence of inhibitory and excitatory synapses and integrated neural circuits. In addition, the convulsant agent 4-AP, evoked epileptiform like activity and increased spike frequency, single cell burst firing, and synchronized network bursting in the organoids, consistent with seizure like activity in these cultures. In further experiments the anticonvulsants, carbamazepine, ethosuximide and diazepam, reduced or blocked 4-AP induced epileptiform-like activity in the organoids at concentrations close to, or within the range of therapeutic dosing for seizure control. Together, the findings reported in this dissertation strongly support the potential value of human pluripotent stem cells in modeling early neural development, neurological disorder and drug investigations in both 2D and 3D cultures.

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