Biomedical Engineering and Bioengineering Commons^™

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 …

Bioelectric Applications For Treatment Of Melanoma, Stephen J. Beebe, Karl H. Schoenbach, Richard Heller

Bioelectrics Publications

Two new cancer therapies apply bioelectric principles. These methods target tumor structures locally and function by applying millisecond electric fields to deliver plasmid DNA encoding cytokines using electrogene transfer (EGT) or by applying rapid rise-time nanosecond pulsed electric fields (nsPEFs). EGT has been used to locally deliver cytokines such as IL-12 to activate an immune response, resulting in bystander effects. NsPEFs locally induce apoptosis-like effects and affect vascular networks, both promoting tumor demise and restoration of normal vascular homeostasis. EGT with IL-12 is in melanoma clinical trials and nsPEFs are used in models with B16F10 melanoma in vitro and in …

Electroporation-Mediated Delivery Of A Naked Dna Plasmid Expressing Vegf To The Porcine Heart Enhances Protein Expression, W. G. Marshall Jr., B. A. Boone, J. D. Burgos, S. I. Gografe, M. K. Baldwin, M. L. Danielson, M. J. Larson, D. R. Caretto, Y. Cruz, B. Ferraro, L. C. Heller, K. E. Ugen, M. J. Jaroszeski, R. Heller

Bioelectrics Publications

Gene therapy is an attractive method for the treatment of cardiovascular disease. However, using current strategies, induction of gene expression at therapeutic levels is often inefficient. In this study, we show a novel electroporation (EP) method to enhance the delivery of a plasmid expressing an angiogenic growth factor (vascular endothelial growth factor, VEGF), which is a molecule previously documented to stimulate revascularization in coronary artery disease. DNA expression plasmids were delivered in vivo to the porcine heart with or without coadministered EP to determine the potential effect of electrically mediated delivery. The results showed that plasmid delivery through EP significantly …

Multiwall Carbon Nanotubes Alter The Thermal Profile And Antibiotic Elution Of Orthopaedic Bone Cement, Alison Carroll Tickle

University of Kentucky Master's Theses

Multiwall carbon nanotubes (MWNTs) have extraordinary mechanical and thermal transport properties. They significantly improve the static and dynamic mechanical properties of acrylic orthopaedic bone cement when added to the dry cement polymer powder. Understanding the role MWNTs play on bone cement polymerization temperatures will lead to improved mechanical integrity of the cement-bone interface in joint arthroplasties. It was determined through thermal testing that MWNTs increased the polymerization time of the methylmethacrylate by 45-460% and decreased the peak exothermic temperature of bone cement with and without antibiotics. The flow of heat produced during polymerizing cement was reduced 25-85% with the addition …

Igf-I Releasing Plga Scaffolds For Growth Plate Regeneration, Sharath Kumar Chinnakavanam Sundararaj

University of Kentucky Master's Theses

Growth plate is a highly organized cartilaginous tissue found at the end of long bones and is responsible for longitudinal growth of the bones. Growth plate fracture leads to retarded growth and unequal limb length, which might have a lifelong effect on a person’s physical stature. This research is a tissue engineering approach for the treatment of growth plate injury. Insulin-like growth factor I (IGF-I), which can stimulate cartilage formation, was encapsulated within PLGA microspheres that were then used to form porous scaffolds. The release profile of the IGF-I from the PLGA scaffold showed a biphasic release pattern. In vitro …

Modeling Changes In Biomass Composition During Microwave-Based Alkali Pretreatment Of Switchgrass, Deepak R. Keshwani, Jay J. Cheng

Department of Agricultural and Biological Systems Engineering: Faculty Publications

This study used two different approaches to model changes in biomass composition during microwave-based pretreatment of switchgrass: kinetic modeling using a time-dependent rate coefficient, and a Mamdani-type fuzzy inference system. In both modeling approaches, the dielectric loss tangent of the alkali reagent and pretreatment time were used as predictors for changes in amounts of lignin, cellulose, and xylan during the pretreatment. Training and testing data sets for development and validation of the models were obtained from pretreatment experiments conducted using 1–3% w/v NaOH (sodium hydroxide) and pretreatment times ranging from 5 to 20 minutes. The kinetic modeling approach for lignin …

Cytocompatible Cross-Linking Of Electrospun Zein Fibers For The Development Of Water-Stable Tissue Engineering Scaffolds, Quiran Jiang, Narendra Reddy, Yiqi Yang

Department of Agricultural and Biological Systems Engineering: Faculty Publications

This paper reports a new method of cross-linking electrospun zein fibers using citric acid as a non-toxic cross-linker to enhance the water stability and cytocompatibility of zein fibers for tissue engineering and other medical applications. The electrospun structure has many advantages over other types of structures and protein-based biomaterials possess unique properties preferred for tissue engineering and other medical applications. However, ultrafine fiber matrices developed from proteins have poor mechanical properties and morphological stability in the aqueous environments required for medical applications. Efforts have been made to improve the water stability of electrospun protein scaffolds using cross-linking and other approaches, …

Microwave-Based Alkali Pretreatment Of Switchgrass And Coastal Bermudagrass For Bioethanol Production, Deepak R. Keshwani, Jay J. Cheng

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Switchgrass and coastal bermudagrass are promising lignocellulosic feedstocks for bioethanol production. However, pretreatment of lignocelluloses is required to improve production of fermentable sugars from enzymatic hydrolysis. Microwave-based alkali pretreatment of switchgrass and coastal bermudagrass was investigated in this study. Pretreatments were carried out by immersing the biomass in dilute alkali reagents and exposing the slurry to microwave radiation at 250 W for residence times ranging from 5 to 20 minutes. Simons’ stain method was used to quantify changes in biomass porosity as a result of the pretreatment. Pretreatments were evaluated based on yields of total reducing sugars, glucose, and xylose. …

Preferential Flow Effects On Subsurface Contaminant Transport In Alluvial Floodplains, Derek M. Heeren, Ron B. Miller, Garey A. Fox, Daniel E. Storm, Todd Halihan, Chad J. Penn

Department of Agricultural and Biological Systems Engineering: Faculty Publications

For sorbing contaminants, transport from upland areas to surface water systems is typically considered to be due to surface runoff, with negligible input from subsurface transport assumed. However, certain conditions can lead to an environment where subsurface transport to streams may be significant. The Ozark region, including parts of Oklahoma, Arkansas, and Missouri, is one such environment, characterized by cherty, gravelly soils and gravel bed streams. Previous research identified a preferential flow path (PFP) at an Ozark floodplain along the Barren Fork Creek in northeastern Oklahoma and demonstrated that even a sorbing contaminant, i.e., phosphorus, can be transported in significant …

Net Radiation Dynamics: Performance Of 20 Daily Net Radiation Models As Related To Model Structure And Intricacy In Two Climates, Suat Irmak, Denis Mutiibwa, José O. Payero

Department of Agricultural and Biological Systems Engineering: Faculty Publications

We compared daily net radiation (R_n) estimates from 19 methods with the ASCE‐EWRI R_n estimates in two climates: Clay Center, Nebraska (sub‐humid) and Davis, California (semi‐arid) for the calendar year. The performances of all 20 methods, including the ASCE‐EWRI R_n method, were then evaluated against R_n data measured over a non‐stressed maize canopy during two growing seasons in 2005 and 2006 at Clay Center. Methods differ in terms of inputs, structure, and equation intricacy. Most methods differ in estimating the cloudiness factor, emissivity (α), and calculating net longwave radiation (R_nl). All methods use …

Synthesis And Characterization Of Magnetic Hydrogel Nanocomposites For Cancer Therapy Applications, Samantha Ann Meenach

University of Kentucky Doctoral Dissertations

Currently, cancer is the second leading cause of death in the United States. Conventional cancer treatment includes chemotherapy, radiation, and surgical resection, but unfortunately, all of these methods have significant drawbacks. Hyperthermia, the heating of cancerous tissues to between 41 and 45°C, has been shown to improve the efficacy of cancer therapy when used in conjunction with irradiation and/or chemotherapy. In this work, a novel method for remotely administering heat is presented. This method involves heating of tumor tissue using hydrogel nanocomposites containing magnetic nanoparticles which can be remotely heated upon exposure to an external alternating magnetic field (AMF). The …

Robust Dynamic Balance Of Ap-1 Transcription Factors In A Neuronal Gene Regulatory Network., Gregory M Miller, Babatunde A Ogunnaike, James S Schwaber, Rajanikanth Vadigepalli

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

BACKGROUND: The octapeptide Angiotensin II is a key hormone that acts via its receptor AT1R in the brainstem to modulate the blood pressure control circuits and thus plays a central role in the cardiac and respiratory homeostasis. This modulation occurs via activation of a complex network of signaling proteins and transcription factors, leading to changes in levels of key genes and proteins. AT1R initiated activity in the nucleus tractus solitarius (NTS), which regulates blood pressure, has been the subject of extensive molecular analysis. But the adaptive network interactions in the NTS response to AT1R, plausibly related to the development of …

Experimental Studies On The Plasma Bullet Propagation And Its Inhibition, Erdinc Karakas, Mounir Laroussi

Electrical & Computer Engineering Faculty Publications

Plasma bullets generated by atmospheric pressure low temperature plasma jets have recently been an active research topic due to their unique properties and their enhanced plasma chemistry. In this paper, experimental insights into the plasma bullet lifetime and its velocity are reported. Data obtained from intensified charge-coupled device camera and time-resolved optical emission spectroscopy (OES) elucidated the existence of a weakly ionized channel between the plasma bullet and its source (such as the plasma pencil). Factors responsible for the inhibition of the propagation of the bullet, such as low helium mole fraction, the magnitude of the applied voltage, and the …