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Biomedical Sciences Seminar Series

Winter 2010 Poster Presentation
February 12, 2009 at 1 pm
Physical Sciences Lobby

Poster #1- Jim O'Hearn

Mapping Oxidation Susceptible Cysteine Thiols on Maize Phosphoenolpyruvate Carboxylase Many enzymes are regulated by reversible oxidation of cysteine residue thiols. Prediction of oxidation susceptible thiols will help scientists identify new sites of redox control. The Cysteine Oxidation Prediction Algorithm (COPA) was employed to predict oxidation susceptibility in phosphoenolpyruvate carboxylase (PEPC). COPA predicted three sites of thiol redox control in PEPC (C308, C335, and C424). Our goal is to experimentally test whether COPA correctly predicted the redox control sites in PEPC. Our approach was to treat PEPC with a thiol alkylating agent and use mass spectrometry to determine which cysteines became alkylated. To test our approach we used bovine serum albumin (BSA) because it is commercially available and has only one free thiol available for alkylation (C34). Iodoacetamide was used to alkylate cysteine residues and trypsin was used to cleave BSA at the carboxyl side of arginine and lysine residues except those followed by proline residues. Peptide fragments were analyzed by Matrix Assisted Laser Desorption/Ionization – Time of Flight Mass Spectrometry (MALDI-TOF MS) and Liquid Chromatography/Mass Spectrometry (LC/MS). Two proteomics tools, PeptideMass and PeptideCutter, were used for mass calculations and prediction of cleavage probabilities.


Poster #2-Macela Leyva

Investigating the Mysteries of Decreased Virus Production in F1-R Sendai Virus Infections Sendai virus, a negative strand RNA virus causes a respiratory tract infection in mice while a variant, called F1-R, causes a systemic infection. To investigate which mutations contribute to the systemic phenotype of F1-R, reverse genetics was used to create variants of Sendai virus with different combinations of the F1-R gene mutations. One reverse genetics virus, RGV0, which contains all F1-R mutations in the F and M genes, was found to behave like F1-R in causing a systemic infection. However, tissue culture studies revealed that RGV0 behaved like wild-type virus in producing more viruses than F1-R, and animal studies suggested that RGV0 was more virulent that either wt or F1-R viruses. We hypothesize that RGV0 is more virulent than wt virus because it causes a systemic infection and that it is more virulent than F1-R because of a higher rate of virus production. To gain a better understanding of the mechanism of decreased virus production in F1-R infections and determine if the decrease is due to an overall decrease in viruses being produced or a decrease in the production of infectious versus non-infectious virus, we have assayed the viruses via hemagglutinin, and egg infectious dose assays. The results indicate that the decrease is in infectious versus non-infectious virus production. We are currently developing both one-step and two-step QRT-PCR protocols that can be used to accurately quantify the number of overall viruses and the ratio of infectious to non-infectious viruses produced during infections of the different variants of Sendai virus.


Poster #3- Eric Cabral

Response-Inhibition ERP Analysis in Patients with Deep Brain Stimulation Authors: Eric Cabral, Rebecca Lee, Mark Liker, Jennifer Hui, Deborah Won Abstract: The capability to discover neurophysiological changes with deep brain stimulation (DBS) will advance improvements in DBS technology. Specifically, cognitive side effects have been observed in Parkinson’s disease (PD) patients after DBS treatment, however current DBS therapy cannot be controlled to avoid these side effects. In order to determine how DBS can be better controlled, we must first determine how DBS is altering essential neural activity which results in changes in cognitive behavior. To analyze cognitive side effects, the electroencephalogram (EEG) is used to measure event-related potentials.


Poster #4-Deborah Laurin

Examining the Factor Structure of the Intimate Partner Violence Acceptance Scale across Gender Intimate partner violence (IPV) is the chief cause of injury and death for women between the ages of 15-44 years (Worden, 2000). IPV is defined as any physical, sexual, psychological, or emotional abuse or threat towards past or current partners. To date there are only 2 published studies examining the factor structure and validity of the intimate partner violence acceptance scale (IPVAS; Smith et al., 2005; Fincham et al., 2008) despite a high prevalence of IPV in the U.S. The IPVAS is confounded by 3 facets; control, abuse, and physical violence. The primary purpose of this study was to examine the underlying factor structure of both previous published models of the IPVAS across gender in terms of structural invariance using a multiple indicator multiple causes (MIMIC) model. Participants consisted of 198 college students (n=132 females; mean age 21.50, SD=5.15) predominately Latino and Asian. Data was collected from an intimate partner violence study among students examining how attitudes, beliefs and behaviors influence perpetration of IPV and prior exposure. Confirmatory Factor Analysis (CFA), using Mplus, revealed that only one of the models met fit indices requirement, however different item response (DIF) existed across gender. Using an exploratory factor analysis within a CFA framework revealed a superior model with no DIF across gender. The new model was subject to CFA and model fit indices were met ?²(54) = 87.363 , p =.002, CFI = .94, TLI = .96, RMSEA = .056. Findings imply a new model free of gender bias across item response and a stable factor structure. The revised model supports the use of the IPVAS among college students to understand how attitudes accepting of IPV may predict future perpetration of IPV.


Poster #5-Evelyn Mendoza

Development and Validation of a Measure to Assess Test Anxiety Test anxiety, a type of “performance anxiety”, is very common among college students and has been known to cause physical, psychological and emotional distress among them. For many students, test anxiety can become so severe that it actually interferes with their concentration and performance. The purpose of this study was to develop and validate a new measure of test anxiety in a multi-cultural college population. 206 students (females= 149; age range = 16 – 49, mean = 21.2) from an urban university completed the scale. The multicultural test anxiety scale (MC-TASS) is a 30 item scale with items rated from 1 (Never) to 6 (All the time). There are two items that address ethnicity by assessing each participant's test anxiety in relation to how others might perceive their ethnic group based on their performance on the test. High internal reliability was obtained for 29 items (Cronbach’s ? = .91). The mean MC-TASS score was 88.6. A significant negative correlation between GPA and MC-TASS scores (r = -.17, p<.05) demonstrated predictive validity for the scale. Concurrent, divergent, and convergent validity were also established, indicating that the MC-TASS can be used with students from diverse ethno-cultural backgrounds.


Poster #6-Albert Nava

Albert Nava Synthesis and Assembly of Mucoadhesive Rf-PEG/ Rf-PEG-PAA Hydrogel Drug Delivery System. Mentor: Yong Ba, Julia Kornfield, and Jeremy Wei Abstract. We produced polyacrylic acid chains on the end of polyethylene glycol polymers that have a fluoroalkyl (Rf) group at their other end. The tri block copolymer is defined as Rf-PEG-PAA. The copolymers were prepared using PEG molecular weights of 6kDa and most recently 10kDa. The PAA block was directly grown on the Rf-PEG macro initiator via atom transfer radical polymerization. PAA blocks will also be attached to the Rf-PEG with the use of click chemistry by coupling of Rf-PEG-N3 with separately made mono-dispersed tertbutyl acrylate.


Poster #7-Natalie A. Sandoval

Novel Putative Function of the Host Defense Protein PLUNC: Carrier of Antimicrobial Cholesteryl Esters in Respiratory Epithelial Secretions Faculty Member: Edith Porter, MD Abstract The innate mucosal defense is the first line of defense against invading microorganisms. In the respiratory tract, antimicrobial effector molecules are secreted by epithelial cells contributing to this innate defense. Our lab has discovered that cholesteryl esters are secreted by respiratory epithelial cells, contributing to the inherent antibacterial activity of nasal fluid. Due to their hydrophobic nature lipids are poorly soluble in aqueous solutions and carrier proteins are required to transport lipids in body fluids. PLUNC (palate, lung, and nasal epithelium clone), a recently discovered member of a lipid transfer protein family, is expressed in airway epithelium. It is a highly hydrophobic protein with putative lipid binding pockets, but its biological function remains unknown. We hypothesize that PLUNC is a carrier for antimicrobial cholesteryl esters in the airways, facilitating the transport of these lipids across the epithelial cell membrane and in extracellular space. We quantified cholesteryl linoleate and cholesteryl arachindonate recovery in aqueous medium in the presence and absence of PLUNC and employed reverse phase High Performance Liquid Chromatography (rpHPLC). Prelimary data suggest that cholesteryl linoleate recovery is increased in the presence of PLUNC. This would signify that PLUNC is a possible carrier for cholesteryl esters.


Poster #8- Luiz Galdino

Improving REDOR Analysis for Multi-Spin Coupled System to Study Complex Protein Structures and Interactions Abstract: The goal of this research is to improve the mathematical model used in Rotational-Echo DOuble Resonance (REDOR) theory of solid-state nuclear magnetic resonance spectroscopy (ssNMR) applied to a spin ½ (S) nucleus coupled to more than one spin ½ (I) nuclei. REDOR ssNMR (simply, REDOR) is commonly used to extract internuclear distances of an S spin coupled to an I spin. Measuring these internuclear distances gives us an insight into molecular structures and information about molecular conformations in thermodynamical states. 13C-19F NMR of adamantane and 1-fluoroadamantane were used as molecular models to find the experimental REDOR curves. Obviously, the current REDOR theory of isolated coupled spin pairs is invalid to predict such multi-spin coupled system. An attempt of a better, yet untested, mathematical model is also presented. This study is an immediate attempt to characterize more complex spin systems in order to better understand the structure and conformation of larger molecules such as protein complexes.


Poster #9- Jhanisus Melendez

Mutational Analysis of K918H in Phsophoenolpyruvate Carboxylase. Phosphoenolpyruvate Carboxylase (PEPc) as an essential photosynthetic enzyme found in C4plants such as maize and sugarcane. PEPc functions distinctly in the assimilation of available CO2 into the four-carbon compound oxaloacetate, however, in maize its principal function is to photosynthetically fix carbon dioxide. The activity of PEPc is modulated both through allosteric regulation and by reversible phosphorylation. Regulatory properties of PEPc include its feedback inhibition by malate, activation by Glucose-6-Phosphate, glycine and the substrate phosphoenol pyruvate (PEP). The aim of our research is to utilize site-directed mutagenesis in order to modify the primary structure of PEPc and assay for enzymatic activity of the mutated protein. Thus far, mutational analysis of the amino acid lysine at position 918 has been substituted by histidine carboxylase to determine its potential role in the allosteric regulation of the PEPc. Once the mutation is confirmed by sequencing, the mutated enzyme obtained from Zea maize will be isolated using E.coli as a vector, and its kinetic regulatory properties will be further explored.


Poster #10-Selma Cuya

Progress toward the identification of mRNA accumulation levels modified in common by MyoD and p53 using global expression analysis Abstract P53, a tumor suppressor that regulates cell cycle arrest and apoptosis, contributes to myogenesis in cultured cells but does not induce myogenesis independently. We and others hypothesize that p53 acts as a backup for the myogenesis regulatory factor MyoD, requiring that p53 and MyoD have some common activities. My objective is to identify genes that are similarly expressed at the level of accumulation of mRNA when either p53 or MyoD is active in a cellular background null for the other activity. Our laboratory constructed two pairs of cell lines from the same p53 null/MyoD non-expressing parent fibroblast cell line. One pair includes cells positive for p53 activity from a zinc-inducible transgene and a non-expressing control line. The second includes cells positive for MyoD activity from a constitutively expressed MyoD transgene and a non-expressing control line. Optimization for conditions under which MyoD activity is readily detectable has been completed for the MyoD-expressing and non-expressing control lines. We are currently optimizing the conditions for inducing p53 activity comparable to that observed in the C2C12 cell line using nutlin, an inhibitor of p53 degradation, and zinc. We are testing the effects of various concentrations of nutlin on p53 activity, using a p53 responsive promoter/luciferase reporter assay. After conditions for p53 activity have been optimized, we will test whether p53 activity has increased expression of the endogenous p53 responsive genes for cyclin dependent kinase inhibitor p21, retinoblastoma, and MDM2, using quantitative RT-PCR. Once appropriate p53 activity has been confirmed, microarray analyses on RNAs from all 4 lines will be done by NimbleGen, and ArrayStar Software will be used for analysis. We will then compare lists of genes shown to be up- and down-regulated and identify common changes in mRNA levels between p53 and MyoD expressing cells. Our results will provide further understanding of how p53 might play a role in myogenesis.


Poster #11- Danilo Santam

"Adapting the Jaipur Foot for use in America"

Abstract: Although technological advances in the artificial limb field have lead to great improvements in the manufacturing and design process of prosthetics, many Americans are not yet able to benefit from these advancements because of the simple fact that most patients are not able to afford such devices. A new artificial limb that is more durable and cost efficient is needed in order to meet the needs of the American people. To achieve this ideal device, one must study the manufacturing process of artificial limbs in addition to the many materials that can be used for prosthetics. The two main areas of our study are the Jaipur foot engineered in India and the use of carbon fiber and fiberglass. After meeting with many prosthetists and physicians, we decided that we would change the material of the Jaipur foot and the knee joint used. We are going to use both carbon fiber and fiberglass for our exoskeletal prosthetic limb to increase the leg’s toughness making it able to withstand the weight needed for use in the United States. In regards to the knee joint we are going to change the material from plastic to carbon fiber in addition to designing a locking mechanism to prevent the patient from falling. If our optimal prosthetic leg is designed, the price will be greatly decreased making these devices accessible to all those in need.



Poster #12- Mario Gallardo

Investigation into the metabolism of hydrogen peroxide damaged creatine kinase
Major: Biology Mentor: Dr. Jamil Momand, Department of Chemistry and Biochemistry, California State University, Los Angeles Rabbit muscle creatine kinase is a homodimer in which each polypeptide subunit has one cysteine residue at its active site on the surface of the protein. Cysteine thiols on the surfaces of proteins with relatively low pKa’s are susceptible to oxidation. Hydrogen peroxide is generated in biological systems and has been shown to oxidize protein cysteine thiols to disulfides, sulfenic acids and sulfinic acids. Depending on protein type, oxidation can inhibit or increase protein activity. Creatine kinase is highly susceptible to oxidation by hydrogen peroxide and we hypothesize that oxidized creatine kinase is targeted for degradation or repair. To test this hypothesis, oxidized forms of creatine kinase were created. By two dimensional gel electrophoresis it was observed that hydrogen peroxide treatment of creatine kinase decreased the pI of the protein from its natural pI of 6.40. Two acidic forms of the protein were created after hydrogen peroxide treatment. Furthermore, after hydrogen peroxide treatment, creatine kinase failed to react with a maleimide-containing molecule indicating that its active site thiol was oxidized. Mass spectrometry will be used to determine the oxidation state of creatine kinase. The assay for protein repair and degradation will be explained.


Poster #13- Rosa Padilla

Cryogen spray cooling (CSC) is an effective method that reduces skin damage during laser therapy in vascular lesions, such as the removal of port wine stains (PWS) birthmarks and other specific dermatology procedures. The objective of this study is to develop a methodology that can be used to determine the boundary conditions, temperature and heat extraction, when cryogenic cooling spray is applied to the surface of the skin prior to laser radiation. To solve this problem a direct problem approach will be used to measure temperature across the sprayed surface of a skin model. These interior measurements along with an inverse heat conduction technique are used to determine the heat transferred at the surface. Using COMSOL, a modeling software package will be used to determine the boundary conditions on the surface of the skin, to achieve a temperature and heat loss profile. Expected results of this study will show us an increase in heat flux and temperature at the center of the sprayed surface, followed by a decrease as time progresses. Learning about the boundary conditions will improve and promote a safe laser therapeutic procedure. It will also enhance our understanding on the cooling rate and efficiency of CSC and how cryo-injury could be prevented.


Poster #14-Orlando Perez

Brain-derived neurotrophic factor hippocampal expression is increased via the recruitment of N-methyl-D-aspartic acid in voluntary wheel-running
exercised rat models

Neurotrophins are macromolecules that play an important role in survival, growth, and plasticity-related signaling in the hippocampus. It has been well documented that physical exercise leads to increased expression of one of these neurotrophins, brain-derived neurotrophic factor (BDNF). One molecule known to be activated during learning tasks, that may be responsible for increased BDNF expression, is the amino acid derivative N-methyl-D-aspartic acid (NMDA). NMDA acts as specific agonist for the NMDA receptor, which in turn imitates the neurotransmitter glutamate at the receptor. In the current study, we wish to assess whether exercise activates the specific NMDA receptor, NR-1. We conducted activation-specific Western analysis for phospho-NR1 and total NR-1 in order to assess the level of activation brought about by three weeks of voluntary wheel-running exercise. Future studies intend to show that there is a recruitment of other molecular pathways for increased BDNF expression.


Poster #15-Paul Harris

Improving the giant magnetoresistance effect by forming a natural
insulating barrier for a spin-tunneling device

Abstract: Most if not all electronics are still based on a system that is driven by the charge of the electron rather than its spin characteristics. This quantum property known as the "spin", has lead to an emerging field of electronics called Spintronics. The orientation of the spin of the electrical carriers allows Spintronics to read, write and store information [1]. Spintronics plays an important role in Magnetic Random Access Memory (MRAM), which is an avenue for the future of electronic devices. MRAM is believed to be a fast nonvolatile memory device and is suppose to have a high density of dynamic RAM (DRAM). Some of flaws seen in DRAM is that it loses data when the power is turned off, which will be remedied with the incorporation of MRAM into technologies. MRAM is one of the many applications to this project. The current research in this field is mainly focused on the exploration of new materials able to transport a coherent spin to distances up to 10²-10³ nm [2]. Our research focus will be on spin polarized transport through an insulator by using electrodes in lithographically patterned nanostructures. The giant magnetoresistance (GMR) effect can be observed in magnetic thin films, which are composed of ferromagnetic layers and nonmagnetic material as a spacer. The ferromagnetic material that will be used in our research is La0.7Sr0.3MnO3 (LSMO), which is nearly half metallic with a very high spin polarization at Fermi Surface. When the ferromagnetic layers are parallel they have a low resistance as opposed to when they are antiparallel. With an applied magnetic field the direction of the magnetization can be altered. Therefore it is the aim of this project is to have a spin polarized transport through an insulator using a half metallic manganite as a spin injector and to observe a magnetoresistance (MR) effect at room temperature.


Poster #16-Rosa Padilla

Methodology of an Inverse Heat Conduction Problem for Cryogen Spray Cooling Applications (CSC) Cryogen spray cooling (CSC) is an effective method that reduces skin damage during laser therapy in vascular lesions, such as the removal of port wine stain (PWS) birthmarks and other specific dermatology procedures. The objective of this study is to develop a methodology that can be used to determine the boundary condition (temperature or heat extraction), necessary to model the heat transfer process that occurs when cryogenic cooling spray is applied to the surface of the skin prior to laser radiation. To solve this problem, a direct approach is first used to find the temperature distribution across the sprayed surface of a skin model. These interior temperature values, along with an inverse heat conduction technique, are then considered to determine the heat transfer at the surface. For both stages of the solution process, the corresponding governing equations are solved by finite-elements-based computer software. The accurate determination of the boundary condition for the heat flux will enhance our understanding of how CSC application can prevent skin damage during laser irradiation.


Poster #17-Corey Baker

The strength-dexterity test using a linear motor and linear/non-linear equations Abstract: A method called the S-D (Strength-Dexterity) test has been developed to quantify the interaction between the strength and dexterity of a fingertip based on the bucking of a spring. My research will replicate and expand the S-D test by using a linear motor controlled by linear and non-linear equations. This allows to chaotic behavior in the motor and can replicate the buckling of a spring to test the strength and dexterity of the hand


Poster #18-Eric Lipari

Numerical Simulations of Thermal Convection in Engineering Systems by COMSOL Multiphysics Fluid flow and heat transfer by convection are important phenomena arising in a variety of engineering applications. Examples include forced and natural convection in heat exchangers, fuel cells, engines, and cooling electronics. To gain a fundamental understanding about the role that thermal convection plays in the performance of these systems, for increased efficiency, cost reduction and environmental concerns, complex mathematical models are developed and solved under various operating conditions. Computer simulations, along with appropriate numerical techniques, either with home-made code or commercial software, are carried out for this purpose. For this work, COMSOL Multiphysics is used to solve the governing equations resulting from the application of the fundamental laws of physics in a variety of settings. COMSOL Multiphysics is a powerful program that can be used to solve the governing equations resulting from multiple physics interactions in a variety of engineering systems. As a way to teach others how fluids act under the influence of convection COMSOL simulations have been conducted in various areas. Before one can teach a subject, one must completely understand it. While setting up the numerous models for simulation a great deal of knowledge about convective heat transfer has been gained. Areas of interest include natural heat convection in various cavities, the laminar flow of fluids in pipes, and boundary layers over flat plates. In the future these simulations can be used in a laboratory environment in conjunction with a class dealing with Convective Heat Transfer or Fluid Dynamics.


Poster #19-DeWayne Anderson


Abstract Tethering coordination complexes to a heterogeneous support is one method to improve the efficiency of homogeneous catalysts. However, the testing of catalysts is often time consuming and requires expending valuable quantities of reactants and catalysts to determine the selectivity and activity of a catalyst. More efficient methods to determine these properties are desirable, but have not been proven with Lewis acid catalysts. This project plans to: one, determine if microfluidic devices (MFDs) can be used on a nano-scale level to determine the enantiomeric composition of products generated from our (Binol)-Cl-Zr-O-Si(O)3-(bulk silica gel) catalyst; two, determine if the same type of qualitative separation that is seen using chiral gas chromatography can be seen using MFDs; and three, determine the enantioselectivity of a catalyst with different substrates if MFDs are able to separate the enantiomeric products from a Lewis acid catalyzed silylcyanation reaction. Commonly used aldehyde substrates in silylcyanation reactions are P-nitrobenzaldehyde, P-trifluoromethylbenzaldehyde, 3-pyridinecarboxaldehyde, P-methylbenzaldehyde, Benzaldehyde, and P-anisaldehyde. In order to determine if MFDs can be used in the detection of enantiomeric products, it is imperative to determine the effect that a catalyst has on “macroscale” reactions with aldehyde substrates using several aldehyde substrates from the list that has been mentioned. This requires determining the efficiency of our Lewis acid catalyst on a macroscale level; the effect that substrates have on catalyst efficiency; the ability of chiral chromatographic media to separate enantiomers; and, the ability to reuse the same chiral chromatographic media in the separation of enantiomers. In order to determine if the (Binol)-Cl-Zr-O-Si(O)3-(bulk silica gel) catalyst works, chiral gas chromatography will be used to determine the enantiomeric composition of products produced from the catalyst. Afterwards, the MFDs can be used on a nano-scale level to determine their use in determining the enantiomeric composition of products from the silylcyanation of various substrates. Once all of the previous steps mentioned have been completed, we should be able to identify promising chromatographic media for MFDs, and gauge the ability of the devices to determine the enantiomeric composition of products generated from a Lewis acid catalyst.


Caridad Wilson
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