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- Creator:
- Wu, YueJia
- Description:
- Objectives. 1. To determine the presence of mesenchymal stem cells (MSC) in rat embryo limb buds and adult rat knee joints. 2. To determine the pharmacological effects of recombinant human GDF-5 (rhGDF-5) on rat MSCs. 3. To determine the effect of rhGDF-5 on load bearing in a rodent model of osteoarthritis. Methods. Fluorescent-Activated Cell Sorting (FACS) was used to identify and purify MSCs from E18 rat embryo and adult rat knee cartilage. Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) was performed to assess the RNA profile of MSCs. qRT-PCR was specifically used to quantify the expression of chondrogenesis markers including Aggrecan (Agc), Type II collagen (Col2), and Sox9 and osteogenesis markers including Runx2 and Type I collagen. An Alamar Blue (AB) assay was utilized to assess effects of rhGDF-5 on MSC proliferation. An Alkaline Phosphatase (ALP) assay was used to study the effects of rhGDF-5 on MSC differentiation. Neuroprobe migration chambers were used to assess rhGDF-5 effects on chondrocyte chemotaxis. In situ hybridization (ISH) was conducted to identify MSC (expression of chondrogenic RNA biomarkers) in rat embryos and in adult knee joints from normal and osteoarthritic rats. Differential weight bearing analysis was assessed using Bioseb's DWB system. Results. MSCs were obtained from E18 rat embryo limb buds and adult rat knee joint cartilage. qRT-PCR showed that MSC comprised pre-osteochondrocytes expressing Agc, Col2a1, Sox9, and GDF-5 RNAs. rhGDF-5 treated MSC showed a dose-dependent increase in AB intensity from Day 1 to Day 14, followed by an increase in rhGDF-5 mediated ALP activity on Day 14 and Day 21. The increased ALP activity coincided with increased Agc, Col2a1, Sox9, and GDF-5 RNA expression indicating that rhGDF-5 selectively promoted chondrogenesis. Greater chemotaxis effect of rhGDF-5 was observed with MSC that presumably were more differentiated after 23 days in culture with rhGDF-5. Following 23 days of treatment with rhGDF-5, MSC appeared as condensations and precartilaginous structures. ISH confirmed the presence of GDF-5, Sox9, and Runx2 in rat embryo hind limbs and in the experimentally-induced osteoarthritic joint of adult animals. DWB analysis revealed significant differential joint loading in the Medial Meniscus Tear (MMT) injured knee, but no reverse differential weight bearing was detected in rhGDF-5 treated rats after a 9-week treatment period. Conclusion. Mesenchymal stem cells are present in rat embryonic limb buds and adult rat knee joint. Our studies show that rhGDF-5 may promote an increase in metabolic activity of MSCs prior to commitment to the chondrocyte lineage. The positive chemotaxic effect of GDF-5 suggests a role in MSC cell homing, cell condensation, and formation of pre-cartilaginous structures. Taken together, GDF-5 is a selective chondrocyte differentiation factor. The presence of MSC in the damaged joint suggests that rhGDF-5 may act to differentiate endogenous MSC to chondrocytes.
- Resource Type:
- Thesis
- Campus Tesim:
- Channel Islands
- Creator:
- Danielson, Rachel
- Description:
- Higher education personnel face a myriad of tasks in the course of their professional duties. The timing and priority of these tasks are sometimes controlled by the staff themselves, but are often determined by campus or external constituents. Five enrollment management staff members were interviewed to identify specific occupational pressures, situations, and challenges in their places of employment. The goal of this study was to determine the common workplace experiences of enrollment management staff and how those circumstances and conditions may affect productivity, professionalism, and purpose.
- Resource Type:
- Thesis
- Campus Tesim:
- Channel Islands
- Creator:
- West, Philip
- Description:
- If one imagines the Gaussian primes to be lily pads in the pond of complex numbers, could a frog hop from the origin to infinity with jumps of bounded size? If the frog was confined to the real number line, the answer is no. Good heuristic arguments exist for it not being possible in the complex plane, but there is still no formal proof for this conjecture. If the frog's journey terminates for a given hop size, it implies that a prime free "moat" greater than the hop size completely surrounds the origin. In the Chauvenet Prize- winning paper "A Stroll Through the Gaussian Primes", Ellen Gethner, Stan Wagon, and Brian Wick [4] explored this problem and by computational methods proved the existence of a square root of 26 -moat. Additionally they proved that prime-free neighborhoods of arbitrary radius k surrounding a Gaussian prime exist. In their concluding remarks, Gethner et al. note that "Similar questions about walks to infinity may be asked for the finitely many imaginary quadratic fields of class number 1."
- Resource Type:
- Thesis
- Campus Tesim:
- Channel Islands
- Department:
- Mathematics
- Creator:
- Gehani, Rohit
- Description:
- The existence of cancer stem cells (CSC) postulates that tumors are organized as a cellular hierarchy and that tumor initiation, growth and cellular heterogeneity are driven by a subset of cells with stem cell like properties. The CSCs are endowed with the ability to self-renew and thereby to proliferate indefinitely. At a functional level, CSCs are characterized by their ability to regenerate in vivo from a single cell into the full spectrum of histology of the tumor of origin and to form spheroid colonies in vitro in an anchorage independent environment. The specific aims for this project include setting up assays that will enable the quantification and the characterization of CSCs and evaluating cell surface markers to enrich for CSC. Additionally, in our in vivo assays, we will compare different mice strains as hosts to our in vivo assays. In order to assess the frequency of CSCs within a solid tumor, we established an in vitro and in vivo limited dilution assay (LDA). A known number of cells were seeded in a low attachment well with stem cell growth media, and the number of spheroids that grew was counted by Optronix GelCount. In an in vivo LDA, immune deficient mice were inoculated with a specific number of cells, and the number of tumor bearing mice was counted. In order to optimize our methods, immortalized colorectal cancer (CRC) cell lines COLO205 and T84 were used as tools to develop LDAs. We were able to determine that the sphere and tumor-forming efficiency of COLO205 was superior to T84, resulting in the primary use of COLO205 cells for assay development. We also aimed to compare the tumor initiating capacity of the COLO205 cell line in order to investigate the effect of the mouse immune system on the read-out of the in vivo tumor formation assay. The result of this experiment was inconclusive; no tumors grew, which is a defect that we could pinpoint to a loss of viability of sorted tumor cells by FACS. We worked with four colorectal cancer models derived from patient tumors and continuously passaged in immune deficient mice. Two models were established from primary tumors obtained from the Amgen Tissue Bank. These tumors were dissociated and cultured in serum-free stem cell growth media on low attachment plates. The other two models were obtained from a company that had continuously passaged the tumors in immune deficient mice. We used these two models to test mouse immune background and effects of irradiation on tumor initiation. Antibodies to extracellular proteins epithelial cell adhesion molecule (EpCAM) and CD133 were used to enrich for a homogenous population of CSCs by sorting protocols. We could not confirm that either of these is a good marker but did find that FACS sorting may affect tumorigenicity and viability of CSCs in our CRC models. The outcome of the CSC enrichment procedure will be important to enable further characterization at the molecular and cellular level of CSC and the identification of potential therapeutic targets that could selectively eliminate CSCs. iv
- Resource Type:
- Thesis
- Campus Tesim:
- Channel Islands
- Creator:
- Fard, Roxana
- Description:
- Bone graft substitutes are commonly used as an alloplastic source for complex bone repair. Human mesenchymal stem cells (hMSCs) have become an idealistic source for bone repair and regeneration due to their potential to differentiate into osteogenic precursors. The purpose of engineering synthetic bone grafts it to successfully find a substitute that is biocompatible, bioresorbable, and has osteoconductive characteristics. The purpose of this study is to construct a bone biocomposite with an optimal amount of biphasic hydroxyapatite/β-tricalcium phosphate (HA-TCP) powder to promote hMSC proliferation with sufficient mechanical stiffness. Results have indicated an increase in metabolic proliferation over a 2-week time period. The constructs seeded with hMSCs exhibited a 3 to 9 fold or greater increase in proliferation depending on the formulation of the construct. This work demonstrates that higher volumes of HA-TCP promote hMSC proliferation in the constructs while maintaining sufficient mechanical stiffness. Optimizing the components of the scaffolds will allow for the most innovative biomimetic bone composite for mesenchymal stem cell differentiation into osteoblasts in an in vivo model.
- Resource Type:
- Thesis
- Campus Tesim:
- Channel Islands
- Creator:
- Cochran, Dana
- Description:
- We examine properties of the Blum Medial Axis (BMA) to improve its effectiveness for automated shape understanding. The BMA has been used to represent objects since the 1960s. Here we examine measurements on the BMA including shape tubularity (ST), erosion thickness (ET), and the extended distance function (EDF). We make connections between the three and use the EDF to find significant paths in 2D shapes. Three shapes are used: a whale tail with only one significant path, a symmetrical flower with a few identical significant paths, and a chicken shape with a few distinct significant paths. We analyze values of the EDF in order to automatically determine the significant directions within a shape. We also establish a relationship between the ST and ET measures that aid in shape identification in future work.
- Resource Type:
- Thesis
- Campus Tesim:
- Channel Islands
- Creator:
- Ruiz, Michael
- Description:
- The study of prime numbers has been an area of interest in mathematics
since antiquity. One natural question one may ask is "How many primes
are there less than or equal to some positive integer?" The first attempts to
answering this were in the late 1700s, culminating in the celebrated Prime
Number Theorem. We investigate how this may be generalized to primes in
an imaginary quadratic number rings in a given sector of the complex plane.
- Resource Type:
- Thesis
- Campus Tesim:
- Channel Islands