Theses and Dissertations from UMD
Permanent URI for this communityhttp://hdl.handle.net/1903/2
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
Browse
6 results
Search Results
Item TOOTH RESORPTION AND RISK FOR ANESTHETIC COMPLICATION DURING ANESTHETIZED DENTAL PROCEDURES IN DOMESTIC FELINES(2019) Jenkins, Emily J; Slopen, Natalie B; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Tooth resorption (TR) in felines may present an increased risk for complications during dental procedures, and it is currently unknown whether oral examination is a valid diagnostic method for type 1 TR. Using existing data from 1,530 felines from a large veterinary hospital in Washington, D.C., I examined the association between type 1 TR and complication under anesthesia during a dental procedure, and the validity of oral examination as a diagnostic tool. Controlling for breed, weight, age, sex, hematocrit, total protein, technician, veterinarian, and presence of oral and systemic disease, type 1 TR was associated with a complication under anesthesia during a dental procedure (p<0.0001). Sensitivity (93.1%) and specificity (97.6%) support the reliability of oral examination for diagnosing type 1 TR. Veterinarians can proactively anticipate lower blood pressures when anesthetizing felines with type 1 TR. There are similarities between TR in humans and felines, and further research is needed on the pathophysiology and health implications of TR in both species.Item Derivation of pluripotent stem cells from blastocysts and somatic cells in the domestic cat (Felis Catus)(2018) Zhou, Ran; Keefer, Carol L; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Pluripotent stem cells in the domestic cat model represent a huge potential for disease modeling, drug screening and regenerative medical treatments for feline species as well as for humans. However, current knowledge on deriving and maintaining stem cells has been obtained primarily from studies in mouse, rat, and human. Difficulties in attaining similar results in cats indicate the necessity to better understand pluripotency in this species. The hypothesis was that inadequate cytokine supplementation results in pluripotency loss along with declining transcription factors expression. The main goal of this project was to assess the effects of selected growth factors and inhibitors, in maintaining pluripotency in embryonic cells, and to attain pluripotency from fibroblasts by controlling expression of exogenous transcription factors. In the first study, conventional cytokine cocktails, leukemia inhibitory factor coupling with glycogen synthase inhibitor 3, and mitogen-activated protein kinase inhibitor (LIF and 2i) could partially maintain pluripotency regulatory circuitry in the cat. In this condition, embryonic cells reached a state that was not fully defined (neither naive nor primed). Overall, cell characterizations revealed a trend of pluripotency loss over time. In the second study, pluripotency was attained by forced expression of inducible exogenous transcription factors (NANOG, POU5F1, CMYC, and SOX2) and cultured in medium supplemented with the same cytokine combination identified in the first study. Notably, unlike previous reports in the cat, colonies with partial pluripotent features could be maintained after the transgenes were silenced. In addition to the protein and transcript markers for pluripotency, lineage marker dynamics were examined in pluripotent cells and embryoid bodies. The outcome suggested the cells generated with LIF and 2i had developed beyond the undifferentiated stage of ICM in expanded blastocyst. Collective results not only challenged the efficacy of the cytokines combinations LIF and 2i in maintaining feline pluripotency, but also suggest direction of research towards the species-specific signaling requirement in embryonic progression and stem cell derivation.Item Experiments with Trapped Ions and Ultrafast Laser Pulses(2016) Johnson, Kale Gifford; Monroe, Christopher; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Since the dawn of quantum information science, laser-cooled trapped atomic ions have been one of the most compelling systems for the physical realization of a quantum computer. By applying qubit state dependent forces to the ions, their collective motional modes can be used as a bus to realize entangling quantum gates. Ultrafast state-dependent kicks [1] can provide a universal set of quantum logic operations, in conjunction with ultrafast single qubit rotations [2], which uses only ultrafast laser pulses. This may present a clearer route to scaling a trapped ion processor [3]. In addition to the role that spin-dependent kicks (SDKs) play in quantum computation, their utility in fundamental quantum mechanics research is also apparent. In this thesis, we present a set of experiments which demonstrate some of the principle properties of SDKs including ion motion independence (we demonstrate single ion thermometry from the ground state to near room temperature and the largest Schrodinger cat state ever created in an oscillator), high speed operations (compared with conventional atom-laser interactions), and multi-qubit entanglement operations with speed that is not fundamentally limited by the trap oscillation frequency. We also present a method to provide higher stability in the radial mode ion oscillation frequencies of a linear radiofrequency (rf) Paul trap--a crucial factor when performing operations on the rf-sensitive modes. Finally, we present the highest atomic position sensitivity measurement of an isolated atom to date of ~0.5 nm Hz^(-1/2) with a minimum uncertainty of 1.7 nm using a 0.6 numerical aperature (NA) lens system, along with a method to correct aberrations and a direct position measurement of ion micromotion (the inherent oscillations of an ion trapped in an oscillating rf field). This development could be used to directly image atom motion in the quantum regime, along with sensing forces at the yoctonewton [10^(-24) N)] scale for gravity sensing, and 3D imaging of atoms from static to higher frequency motion. These ultrafast atomic qubit manipulation tools demonstrate inherent advantages over conventional techniques, offering a fundamentally distinct regime of control and speed not previously achievable.Item Insertion and Evolution of an Endogenous Retrovirus into KIT is Responsible for Multiple Phenotypes at the White Locus in the Domestic Cat(2014) Wallace, Andrea Brynne; Menotti-Raymond, Marilyn; Mount, Stephen M; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The Dominant White locus (W) in the domestic cat demonstrates pleiotropic effects exhibiting complete penetrance for absence of coat pigmentation and incomplete penetrance for deafness and iris hypopigmentation. I preformed linkage analysis using a pedigree segregating White to identify KIT (Chr. B1), as the feline W locus. Segregation and sequence analysis of the KIT gene in two pedigrees (P1 and P2) revealed the remarkable retrotransposition and evolution of a feline endogenous retrovirus (FERV1) as responsible for two distinct phenotypes of the W locus, Dominant White, and White Spotting. The retrotransposition interrupts a DNase I hypersensitive site in KIT intron 1 that was previously demonstrated to regulate temporal and tissue specific expression of KIT in mice. A large population-genetic survey of cats (n=269), supports our findings and demonstrates statistical significance of the FERV1 LTR and full-length element with Dominant White (p < 0.0001) and White Spotting (p< 0.0001), respectively.Item THE IMPACT OF CULTURE MEDIA ON THE IN VITRO PRODUCTION OF CAT BLASTOCYSTS AND EXPLANT QUALITY(2012) Nestle, Emily; Keefer, Carol L; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Continued improvements in embryo culture media composition allow for the growth of high quality blastocysts, which can be used to derive embryonic stem cells (ESCs). ESCs are capable of becoming any cell type in the body making them a valuable research tool for therapeutic and regenerative research, while furthering our understanding of embryonic development and cell differentiation. The domestic cat is an important model species for both human medicine and wild felids. Cat embryo culture produces blastocysts at a rate far below that of the mouse and initial attempts at deriving cat ESCs have resulted in embryonic stem-like cells, which cannot be maintained indefinitely. In this study we assessed and compared the quality of cat blastocysts produced in vitro using two commercial human blastocyst growth media, and the maintenance of pluripotency markers OCT-4 and NANOG in inner cell mass explants from in vitro produced blastocysts over 14 days.Item Priming with Oral Progestin Before Ovulation Induction Facilitates Ovarian Function in the Cat (Felis catus)(2007-11-21) Bauer, Rosemary Aileen; Ottinger, Mary Ann; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Artificial insemination (AI) has been developed in multiple felid species as a tool for retaining gene diversity in threatened or endangered populations. Yet, pregnancy success remains low (< 5%) following AI in most felids, particularly in species that spontaneously ovulate. This failure has been attributed to variable ovarian status at the time of insemination and adverse residual effects caused by exogenous gonadotropins used to induce ovulation. Using the domestic cat as a research model, a new AI regimen that incorporated short-term ovarian suppression with oral progestin (altrenogest; ALT) before ovulation induction was investigated. The hypothesis was that oral progestin priming would prevent spontaneous ovulation, improve ovarian responsiveness to exogenous gonadotropins and mitigate adverse effects caused by persistent gonadotropin actions. Specific objectives were to: (1) increase fundamental understanding of the mechanisms controlling ovarian function; and (2) characterize how oral progestin priming prior to exogenous gonadotropin treatment influences ovarian responsiveness, fertilization, early embryonic development and luteal function in the cat. Fecal hormone monitoring was used to establish an ALT dosage that provides rapid, reversible ovarian suppression with no residual effects on estrous cyclicity. With this information, the influence of progestin priming on ovarian responsiveness to exogenous gonadotropin dosage was investigated. Priming increased ovarian sensitivity to gonadotropins, supporting the use of lower dosages for ovulation induction. Next, in vivo fertilization success and in vitro early embryonic development was characterized following laparoscopic, intrauterine AI in cats treated with ALT. Progestin-primed females demonstrated a good ovarian response to ovulation induction and more consistent embryonic development, compared to cats treated with gonadotropins alone. Furthermore, endocrine data revealed that normal luteal progesterone levels were maintained only in queens primed with the oral progestin. Finally, histology and quantitative RT-PCR were used to characterize the differential effects on luteal function observed. Aberrant CL progesterone production was not associated with changes in ovarian morphology, or the expression of six specific genes associated with luteal function and progesterone biosynthesis. Overall, these studies increased knowledge of domestic cat reproductive physiology and improved understanding of ovarian suppression for enhanced AI efficiency in felids.