Biomedical Engineering and Bioengineering Commons^™

Understanding The Molecular Dynamics Of Ypel3 And Fhit Gene Expression, Kevin Daniel Kelley

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A comprehensive understanding of the molecular signaling pathways that regulate cell growth and proliferation is essential in the realization of new therapeutic options to facilitate early detection and eradication of malignancy. Understanding the transcriptional regulation of the YPEL3 and FHIT genes forms the basis of this dissertation. YPEL3, or Yippee-like 3, is a newly identified p53 target gene that inhibits tumor cell growth and is thus itself, a novel tumor suppressor gene. FHIT, or Fragile histidine triad, is a well known tumor suppressor gene and is regulated at the transcriptional level by another growth inhibitory protein, FOXO3a, a Forkhead box …

A Biomechanical Comparison Of Locking Compression Plate Constructs With Plugs/Screws In Osteoporotic Bone Model, Krishna P. Desai

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Locking compression plates are proven to be safe for use in open reduction and internal fixation (ORIF) especially in osteoporotic bones. Because of various combinations of holes, the system provides more options for clinicians to use either locking screws or non-locking screws. This clinical research introduces screw like plugs which can be used along with the screws in case of locking compression plates. Experimental work was performed to determine the effectiveness of the plugs. The results showed that there is not a significant difference between the groups which used plugs and did not use the plugs, both in case of …

Extent And Effects Of Selection To Reduce Synthetic Cost Of Highly Expressed Proteins, Esley Marvin Heizer Jr

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Organisms that preferentially utilize less biosynthetically expensive amino acids in highly expressed genes exhibit metabolic efficiency. Exploration of this phenomenon has been limited to six prokaryotes.

I present a large scale analysis of metabolic efficiency in prokaryotic organisms and analysis of two eukaryotes (Saccharomyces cerevisiae and humans). Examination of 73 bacteria reveals the presence of metabolic efficiency in 66 organisms. The average correlation between amino acid biosynthetic cost and CAI scores in these organisms is -0.21. The seven organisms that did not exhibit metabolic efficiency are all Lactobacilli and highly auxotrophic. Saccharomyces cerevisiae exhibits significant trends between average amino acid …

Population Fit Threshold: Fully Automated Signal Map Generation For Baseline Correction In Nmr-Based Metabolomics, Daniel C. Homer

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Baseline correction of NMR-based metabolomic spectra is a key step in data processing to elucidate biomarkers of diseased and toxic states. Automated baseline correction methods often use human-selected parameters. Presented is a method for automated baseline correction using parameters selected from and without manipulation of the spectrum. The focus is on generating an accurate signal map based on the differentiating characteristics of baseline noise and signal. The presented method of signal map generation and baseline correction was developed and tested on 13C and 1H NMR spectra. The spectra were as simple as chemical standards containing less than 25 signal peaks …

Induction Of P53 Dependent Cellular Senescence Through Hdmx Inhibition Or Ypel3 Expression, Kelly Lynn Robbins Miller

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Mutations in p53 that compromise its function have been reported in approximately half of all human cancers (Vousden et al., 2002). The other half of human tumors that retain wild-type p53 have a dysfunctional p53 pathway through other mechanisms (Wade et al., 2009). Activation of p53 leads to cell cycle arrest, DNA repair, apoptosis and senescence, however, the pathway leading to cellular senescence is the focus of this study. Cellular senescence is a process leading to irreversible arrest of cell division. Under normal physiologic conditions, the activity of p53 is kept in check by its negative regulators, Mdm2 and MdmX. …

Cytochrome C Oxidase From Rhodobacter Sphaeroides: Oligomeric Structure In The Phospholipid Bilayer And The Structural And Functional Effects Of A C-Terminal Truncation In Subunit Iii, Teresa L. Cvetkov

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Cytochrome c oxidase (COX) of the mitochondrial electron transport chain catalyzes the reduction of oxygen to water while concomitantly translocating protons across the inner mitochondrial membrane. This two part dissertation is a structural and functional investigation of COX using the bacterial model system from Rhodobacter sphaeroides (R.sph.).

First, the oligomeric structure of R.sph. COX within the lipid bilayer was investigated using discontinuous sucrose gradient ultracentrifugation. Utilizing this technique, liposomes containing R.sph. COX (pCOV) were separated from liposomes lacking enzyme (COV). The net buffering capacity and degree of light scattering per COX molecule were reduced in pCOVs, making them well suited …

Finding Cadaveric Human Head Masses And Center Of Gravity: A Comparison Of Direct Measurement To 3d Ing, Grant Corwin Roush

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Mass properties of the human head are critical elements in developing neck injury threshold criteria in acceleration and impact environments. In order to accurately simulate the dynamics of the head in impact and acceleration environments, valid mass properties data for the human head must exist.

The purpose of this study was two-fold: First, to directly measure and generate a useful data set of human head mass properties and anthropometry, and second, compare the results from the direct measurement to measurements obtained using computed tomographic (CT) analyses of the human head. Four cadaveric human heads, all male, were measured.

For the …

Computer-Based Skeletal Age Assessment Using Hand/Wrist Radiographs In Children 8-18 Years Old, Zhihong Ni

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Children's skeletons mature at different rates, and they can be affected by a variety of factors including disease, hormone imbalance or genetics. The assessment of skeletal maturity is a frequently performed procedure that allows the detection of hormonal, growth or genetic disorders. Several methods have been developed to estimate skeletal maturity. Most methods evaluate hand/wrist radiographs using indicators such as the ratios of various bone widths, the onset of the ossification of epiphysis and epiphyseal-diaphyseal fusion. Among those methods, the FELS method differs from others in the application of different grades to each indicator and the provision of a confidence …

Charaterization Of Chlorpyrifos Toxicity On The Pancreatic Beta Cell Line Rinm5f, Zhongyu Yan

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Chlorpyrifos (CPF) is a well-known organophosphate (OP) insecticide that inhibits acetylcholinesterase (AChE). Organophosphates have been shown to induce hyperglycemia in both humans and animals that cannot be explained by AChE inhibition alone. Pancreatic β-cells are responsible for secreting insulin and playing a fundamental role in glucose homeostasis. The aim of this research was to investigate CPF toxicity on the insulin secreting β-cell line RINm5f (RIN). In the first part of this dissertation, we determined that cytotoxic concentrations of CPF between 50 µM and 200 µM induced a dose-dependent increase in RIN cell apoptotic and necrotic death (p<0.05). Lower doses, i.e., 5-25 µM did not induce apoptosis or necrosis. In further mechanistic studies, inhibitors of c-Jun N-terminal kinase (JNK) and P38 pathways, i.e., SP600125 and SB202190, successfully attenuated CPF-induced apoptosis (p<0.05), suggesting cell death is mediated by JNK and/or p38. In addition, N-Acetyl-L-cysteine (NAC), an antioxidant, inhibited apoptosis suggesting that oxidative stress is also involved in RIN cell death. In the second part of this dissertation, low dose CPF's effects on insulin synthesis and secretion was studied. Our results showed that RIN cells treated with CPF for 4 hr exhibited a dose-dependent decrease in insulin secretion in response to stimulation by 50 mM potassium (p<0.05). Insulin secretion stimulated by 25 mM glucose also showed significant decreases upon incubation with various doses of CPF (p<0.05). Insulin synthesis involves proteolytic cleavage of proinsulin at two specific sites. The enzymes responsible for promoting proinsulin cleavage, i.e, prohormone convertase (PC) 1/3 and 2 (PC2), contain a serine hydrolase catalytic triad, His-Asp-Ser, similar to AChE. CPF modification of PC enzymes similar to AChE, could potentially interrupt the conversion of proinsulin to insulin and disrupt insulin secretion. PC2 enzyme activity was significantly inhibited by CPF at concentrations as low as 10 µM (p<0.01). RIN cells, for the first time, were found to secrete proinsulin was through a constitutive instead of a regulated pathway. In summary, our results show that CPF not only exerts a direct cytotoxic effect at concentrations above 50 µM, but also significantly impairs insulin secretion at lower doses. Low dose CPF could potentially affect endocrine function in vivo by inhibiting the proinsulin processing enzyme PC2.

Radio Frequency Controlled Stimulation Of Intracellular Gold Or Silver Nanoparticle Conjugates For Use As Potential Sensors Or Modulators Of Biological Function, Richard Craig Murdock

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The objective of this investigation was to further explore the ability of a radio frequency (RF) signal to interact with metal nanoparticles (NPs) for the purposes of remote stimulation or control of cellular processes. Gold and silver NPs have shown the ability to be heated by electromagnetic frequencies, especially for the purpose of deactivating abnormal cells. However, the heating of the NPs in these previous studies was constant and uncontrolled. For this study, our hypothesis was by investigating the RF heating characteristics of NPs and its impact on surface functionalizations, a remotely stimulated control mechanism can be developed at the …

Characterization And Improvement Of A Cone-Beam Ct Scanner For Quantitative Imaging, Jimish Dilip Joshi

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Computed tomography (CT) has various applications in different fields. In our case, the cone-beam CT scanner is used in the industrial field for qualitative and quantitative assessment of Procter and Gamble products. The Flash CT scanner, on which we do our research, has a microfocus x-ray tube, a detector size of 30 cm x 40 cm and a rotating stage for the object to be imaged. The x-ray tube can be operated up to 225 kV. Non-linearities in the response of the detector, scatter and beam hardening may cause false interpretations of the image values. To allow appropriate assessment of …

Cellular Effects Of Replicating A Polypurine-Polypyrimidine Sequence And The Interactions Of Due-B With Replication Proteins, Shere Lynne Myers

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This work investigates two questions regarding DNA replication. The first aim examines the interactions of DUE-B with replication proteins and the second explores the cellular effects of replicating a polypurine polypyrimidine sequence in human cells.

DUE-B siRNA decreases the chromatin binding of essential replication proteins Cdc45, PCNA and RPA. DUE-B also co-immunoprecipitates with Cdc45 and TopBP1. In vitro kinase assays suggest that the checkpoint protein ATR may phosphorylate DUE-B. These experiments lend further evidence that DUE-B plays an important role in the initiation of eukaryotic DNA replication.

To investigate the effects of replicating a polypurine-polypyrimidine sequence prone to secondary structure …

Differential Regulation Of Vitamin D Receptor (Vdr) By P53, P63 And P73, Ramakrishna Kommagani

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The tumor suppressor p53 is the single most altered gene in human cancers. p53 homologues, p63 and p73 play a major role in development and in human cancer. Both p63and p73-null mice exhibit profound developmental abnormalities, suggesting a vital role for p63 and p73 in development. Although the role of p73 in human cancers is well established, the role of p63 still remains to be understood. While p63 plays a major role in development, p73 plays a major role in tumor suppression as well as in development. Although a functional co-operation is evident between each member of p53 family, additional …

Cellular Function Of The Ia-Motoneuron Circuit Following Peripheral Nerve Regeneration, Katie Leigh Bullinger

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Successful regeneration of a severed peripheral nerve is insufficient to restore the stretch reflex. This deficit occurs despite successful muscle reinnervation and functional restoration of the circuit components. For example, Ia afferents encode muscle stretch, Ia-motoneuron synapses reform to the extent of restoring low frequency transmission, and activation of motoneurons results in muscle force output. However, when recording intracellularly from reinnervated rat motoneurons during ramp hold and release muscle stretch, no excitatory synaptic potentials are detected in 2/3 motoneurons (Haftel et al., 2005), a clear sign that the synapses connecting Ia afferents with motoneurons are physiologically disrupted. This thesis examines …

Timing-Pulse Measurement And Detector Calibration Of The Osteoquant, Binu Eapen Enchakalody

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The OsteoQuant is a second-generation pQCT scanner, which can provide precisedensity assessment of bone. The scanner is being upgraded with an x-ray tube radiation source and a semiconductor CZT detector. This thesis provides solutions for two issues: motion-detector timing and dead-time/beam-hardening corrections. During translation, the motion-control system of the scanner repositions the source and detector by small intervals. However, the detector collects photon counts asynchronously with respect to the motor-timing pulses and reads photon counts (frames) at regular intervals based on its own clock. Since there needs to be correspondence between source/detector location and detector readout, the first part of …

Ion Transport Mechanisms During Hyposmotic Regulatory And Isosmotic Apoptotic Volume Decreases In A Human Lens Epithelial Cells Line, Ameet Ajit Chimote

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Living cells maintain constant volume in response to physiological stresses by altering trans-membrane ion, solute and water flow. In the present study, early and late membrane transport changes in human lens epithelial (HLE-B3) cells under hyposmotic and apoptotic stress were compared. Cell potassium (Ki), rubidium (Rbi)-uptake and water content were measured by atomic absorption spectrophotometry and gravimetry, respectively. Intracellular chloride concentration [Cl]i was determined with the fluorescence dye N- (ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (MQAE), during regulatory volume decrease (RVD) after hyposmotic stress and apoptotic volume decrease (AVD) induced by staurosporine (STP), a protein-kinase inhibitor. Cell water increased in hyposmotic balanced salt solution …

The In Vitro Interactions Between Tubulin And Hiv-1 Rev Require Rev's Multimerization And Arginine-Rich Motifs, Amit Sharma

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Rev is a 13 kDa regulatory HIV protein essential for viral replication. It trans-activates expression of late viral proteins by multimerizing onto target mRNA and promoting their export into the cytoplasm. During attempts to find the solution conditions needed to study Rev structure, Watts et al. (2000) discovered that Rev depolymerizes microtubules (MTs) in vitro through the formation of ringed tubulin intermediates called Rev-tubulin toroids (RTTs). Rev interactions with MTs are specific and are thought to mimic the mechanism of Kinesin-13 proteins, themselves potent MT depolymerases that regulate the assembly of the mitotic spindle. If Rev and Kinesin-13 proteins share …

Graphical User Interface (Gui) To Study Different Reconstruction Algorithms In Computed Tomography, Shital K. Abhange

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Computed tomography (CT) imaging relies on computational algorithms to reconstruct images from projections gathered from the CT scan. Depending on the scanner geometry, different types of reconstruction algorithms can be used. To study these different types of reconstruction algorithms in a user-friendly way, a software tool was built. The aim of the thesis was to provide a software platform to access a number of previously implemented reconstruction algorithms with ease and minimal knowledge of the reconstruction code. The goal was accomplished by building a Graphical User Interface (GUI) using MATLAB 7.7.0 (R2008b). In addition to creating mathematical objects and invoking …

Small Conductance Calcium-Activated Potassium (Sk) Channels In Mammalian Spinal Motoneurons, Zhihui Deng

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Three homologous small conductance calcium-activated potassium (SK) channel subunits (SK1, SK2, and SK3) are expressed in distinct and overlapping patterns in mammalian central nervous system. SK channels likely mediate the medium afterhyperpolarization (mAHP), which plays an essential role in regulating neuron repetitive firing frequency. In spinal motoneurons (MNs) the mAHP duration is shorter on average in fast (F-type) MNs than that in slow (S-type) MNs. To better understand the molecular basis for mAHP, we determined the expression and sub-cellular distribution of SK channels in normal, axonally-injured, and developing spinal MNs in vivo using immunohistochemistry and quantitative confocal imaging techniques.

SK2 …

Induction Of Socs-1 In Hsv-1-Infected Murine Keratinocytes: A Mechanism Of Inhibition Of Interferon Gamma, Kenneth Gene Frey

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Epidermal cells such as keratinocytes are the major site of Herpes Simplex Virus Type 1 (HSV-1) replication in active primary or recurring herpes infection. In this study, a murine keratinocyte cell line (HEL-30) was shown to be refractory to IFNγ induction of an antiviral state to HSV-1 infection, while IFNγ did induce an antiviral state in a murine fibroblast cell line (L929). Particularly, IFN-gamma and its peptide mimetic protected fibrobasts from viral-induced cytopathic effect while the keratinocytes were destroyed by the infection. Suppressor of cytokine synthesis-1 (SOCS-1) a negative regulator of IFNγ, was hypothesized to be responsible for the refractiveness …

Embryonic And Postnatal Development Of The Neural Circuitry Involved In Motor Control, Valerie Cari Ann Siembab

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The development of locomotion is believed to result from the maturation of the spinal circuits controlling motor output, however little is known about its mechanisms. To shed some light into this process we studied the development of the synaptic connectivity of two spinal inhibitory interneurons. Adult motoneurons are controlled by inhibitory networks that include recurrent and reciprocal inhibition (Pierrot-Deseilligny & Burke, 2005). Each is modulated by different ventral horn spinal interneurons that display synaptic connectivity adapted to their function: Renshaw cells (RCs) mediate recurrent inhibition, receive excitatory inputs from motor axons and inhibit homonymous and synergistic motoneurons; while Ia inhibitory …

Hif-1 Alpha: A Master Regulator Of Trophoblast Differentiation And Placental Development, Kashmira Kulkarni

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Early embryonic development occurs under low oxygen levels. The placenta is an organ transiently formed during pregnancy and plays a crucial role during development of the embryo. Alterations in the placental structure or function have been associated with the pathologies such as preeclampsia in humans. In mammals, the hypoxia inducible factor (HIF) transcription factors have been identified as the major regulators of cellular responses in low oxygen. In the current study, we investigated the effects of low oxygen on the differentiation of trophoblast stem cells, lineage committed trophoblast giant cells and labyrinthine lineage-committed cells. We examined the effects of an …

Central Mechanisms Regulating Pituitary-Adrenal Activity In Infant Guinea Pigs (Cavia Porcellus) During Exposure To Psychological Stressors: Independent And Combined Effects Of Maternal Separation And Novelty, Deborah Suzanne Maken

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Separation from the maternal attachment figure, particularly when it occurs in a novel or threatening environment, reliably increases pituitary-adrenal activity in a number of species, and is thought to increase later susceptibility to psychopathology in humans. However, little is known about the central mechanisms mediating these effects. Therefore, I investigated cortisol and ACTH levels in plasma, corticotropin-releasing factor (CRF) mRNA expression in the hypothalamic paraventricular nucleus (PVN), and c-Fos activity in a circuit [medial amygdala (MeA)- bed nucleus of the stria terminalus (BNST)] thought to drive pituitary-adrenal activity during exposure to psychological stressors, as well as in the PVN. Measurements …

Genetic Differentiation In Ambystomatid Salamanders Across A Fragmented Landscape, Joseph E. Bartoszek

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It is generally recognized that amphibian populations declining across the globe. Habitat loss is the primary cause of decline. The salamander family Ambystomatidae has experienced significantly more rapid decline than the average for amphibians. Coefficients of Conservatism (CoC) have been developed for amphibians in Ohio. These are based primarily on habitat requirements with high CoCs for amphibians with stringent habitat requirements (e.g. vernal pools associated with large, intact, undisturbed forest), and low CoCs for amphibians with less stringent habitat requirements. Genetic diversity in five species and one hybrid complex of ambystomatid salamander in southwest Ohio were examined and compared to …

Characterization Of Excitatory Amino Acid Neurotransmitters At Motoneuron Synapses Contacting Renshaw Cells, Dannette Shanon Richards

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Motoneurons are among the best studied neurons in the central nervous system. The motoneuron synapses have been well characterized in the periphery where they release acetylcholine at the neuromuscular junction. However excitatory amino acids also seem to be released from motoneuron terminals in the periphery, and centrally at their synapses contacting Renshaw cells. Although excitatory amino acids are suggested to be released from motoneuron synapses it is not known which excitatory amino acids (either aspartate or glutamate) are released, nor is the mechanism for their release known. To examine the presence and mechanism of release for aspartate and glutamate at …

The Effects Of Chronic Hypoxia And Substance P On The Chemosensitive Response Of Individual Nucleus Tractus Solitarius (Nts) Neurons From Adult Rats, Nicole L. Nichols

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The chemosensitive responses of individual nucleus tractus solitarius (NTS) neurons from neonatal rats have been extensively studied, but few studies have examined the chemosensitive responses of NTS neurons from adult rats. In addition, environmental conditions have been used to mimic respiratory diseases/disorders in rats to study how the cellular responses of individual neurons change to regulate breathing during pathological conditions. Lastly, it has been shown that substance P release increases in response to hypoxia from peripheral afferents that primarily terminate in the caudal NTS. We studied the effect of chronic hypoxia (CHx) and substance P on the response to hypercapnia …

Novel Redox And Dna-Dependent Conformational Changes In Human Ku, A Dna-Double Strand Break Repair Protein, Jason Alexander Lehman

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Ionizing radiation (IR) and radiomimetic drugs used in cancer chemotherapy cause DNA double-strand breaks which are repaired by the nonhomologous end joining (NHEJ) pathway. Ku is a heterodimeric protein comprised of 70 and 80 kDa subunits and recognizes free DNA ends. Once Ku is bound to DNA, it binds to the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), and forms a heterotrimeric DNA-PK complex for repair and damage signaling.

We have analyzed the Ku protein using multiple biochemical techniques and uncovered a novel reversible redox change (Andrews, Lehman and Turchi, (2006) JBC 281(19):13596-603). From this data, we hypothesized that a redox-dependent …

Performance Analysis Of Quantitative Bone Measurement With Spiral, Multi-Detector Ct Scanners, Shruti Gupta

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The measure of bone strength and fracture risk assessment is based primarily on bone mineral density (BMD). Computed tomography (CT), a frequently used radiographic technique that provides cross-sectional images, can be used for BMD quantification. Called quantitative computed tomography (QCT), it determines true volumetric density and also differentiates between trabecular and cortical bone. As a result, QCT improves the ability to detect early changes in trabecular BMD accurately and precisely.

The introduction of helical CT for quantitative analysis introduces new complexities. Even though using multi-detector helical CT for BMD assessment is being suggested, a detailed analysis of its validity is …

Histogram-Based Template Matching Object Detection In Images With Varying Brightness And Contrast, Christina Da-Wann Schrider

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Our challenge was to develop a semi-automatic target detection algorithm to aid human operators in locating potential targets within images. In contrast to currently available methods, our approach is relatively insensitive to image brightness, image contrast and object orientation. Working on overlapping image blocks, we used a sliding difference method of histogram matching. Incrementally sliding the histograms of the known object template and the image region of interest (ROI) together, the sum of absolute histogram differences was calculated. The minimum of the resultant array was stored in the corresponding spatial position of a response surface matrix. Local minima of the …

Biomechanical Evaluation Of Locked And Non-Locked Constructs Under Axial And Torsion Loading, Vinit A. Patel

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Locking compression plates are proven to be safe for use in open reduction and internal fixation (ORIF). The ORIF is a procedure performed to treat fractures. It has various combination of holes, the system provides more options for clinicians to use either locking screw or non-locking screws. This thesis investigates and determines the best construct with special locking and non-locking screws under both axial and torsion loading. Twenty femur constructs were assembled with 2 cm osteotomy gap between femur shaft and condyle, bridged with 4.5 mm - 10 holes condyle plates. Femurs were divided in to 4 groups according to …