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Biomedical Sciences Seminar Series
Winter 2008 Poster Presentation

January 25, 2008 at 1 pm

Physical Sciences Lobby

Poster #1-James Nunnelley
Hydroxamate and hydroxypyridonate derivatives of the E. coli
siderophore enterobactin

James Nunnelley, Thuy Nhi Nguyen, Roberto Amador,
Guillermo Flores, and Carlos Gutierrez
We are testing the notion that hydroxamate siderophores can be improved through preorganization of the hexadentate binding unit.  Using the catecholate siderophore enterobactin, whose exceptional binding is attributed in part to preorganization of the binding units, as a model, we are replacing the catechol units on the enterobactin triserine lactone core with hydroxamate (and pyridonate) subunits.  The hybrid target molecules trishydroxamate would presumably have its three binding units organized into a hexadentate ligand predisposed to iron binding by the enterobactin triserine lactone backbone.  Our target molecules were characterized through HNMR, C-13 NMR, and FTIR spectroscopy.  We report progress in the synthesis of these hybrid siderophores.   top

Poster #2-Erika Garcia

Chemically Robust Microfluidic Chips and Related Applications
Erika Garcia1, George Maltezos2, Axel Scherer2, Grady Hanrahan1
and Frank A. Gomez

A current problem in microfluidics is that the main polymer used to fabricate microfluidic devices (MDs), poly(dimethylsiloxane) (PDMS), is not very compatible with most organic solvents. Known fluorinated polymers are more chemically robust than PDMS but, historically, they have been nearly impossible to use in MD fabrication, especially when using multilayer soft lithography (MSL) due to the difficulty of bonding layers made of ‘‘non-stick’’ fluoropolymers. In this study, we describe the fabrication of microfluidic chips using a perfluoropolyether, termed Sifel, in a single monolithic layer and the incorporation of a three-dimensional (3-D) valve within the chip. With our new 3-D valve design we can fabricate MDs from fluorinated compounds in a single monolithic layer that is resistant to most organic solvents with minimal swelling. The fabrication of Sifel-based MDs using these techniques has great potential in chemical synthesis and

Poster #3- Anita Mihecoby
Differences between Latinos and European American
college students in choice of majors.
The importance of college degrees is emphasized in order to achieve social mobility. However, a mean difference in annual income of $10,781 exists for Latinos with advanced degrees compared to European Americans of equal education (U.S. Census Bureau, 2000). Differences in academic fields of study may be a factor (Davies & Guppy, 1997). The aim of this study was to examine differences between Latino and European American college freshmen in their choice of major. It was hypothesized that Latinos would have a higher percentage of majors in human services and a lower percentage in business and economics majors, compared to European Americans.
            Participants were 269 Latino (72 male, 197 female) and 36 European American (13 male, 23 female) freshmen. Mean age was 18.03 years (SD = 1.6). Majors were collapsed into 5 categories: arts and letters, sciences, business and economics, human services, and undecided.
            Chi-square analysis showed that more Latinos (54.7%) than European Americans (27.8%) chose majors in human services, χ2 [4] = .013, p = .05. In contrast, more European Americans chose majors in business and economics (30.6%) and sciences (27.8 %) than Latinos, (14.6% and 15%, respectively). In summary, Latinos more often declared majors within the college of human services, and European Americans more often chose majors in business, economics and sciences. Latino’s choice of majors that lead to less lucrative careers may limit their progress towards social equality. top

Poster #4- Alberto Izarrarraz

Explicit Stochastic Models for the Population Dynamics of Tribolium

Models that incorporate random processes are useful tools to study the dynamics of ecological populations.  Most stochastic models are phenomenological nonlinear deterministic equations with an added random term representing “noise.”  However, noise does not explain the mechanistic nature of random processes within the population.  An explicit stochastic model provides insight on the mechanisms leading to randomness.  I propose to develop explicit demographic stochastic models for insects of the genus Tribolium, estimate parameters for each model using data from laboratory populations, and compare the predictive ability of the models using time series population data. The models will take into account a variety of potential sources of demographic stochasticity, such as a deviations in the sex ratio, different birth and survival rates among individuals, and different rates of development. This project can serve as a paradigm for explicit stochastic modeling and connecting these types of models to experimental data. top

Poster #5-Laura Martinez
Identification of activities shared by MyoD and p53
by global expression analysisLaura E. Martinez
; Sandra B. Sharp, Ph.D.; Xiu Zhu Sun, M.D.; Mesfin Gewe
Department of Biological Sciences at the California State University, Los Angeles
MyoD is a muscle-specific transcription regulator and one of the earliest markers of myogenic commitment. It is transcribed from one of a family of four myogenesis determination genes, each of which has been shown to induce myogenesis when expressed from a transgene in cultured non-muscle cells.   P53, a tumor suppressor known to regulate cell cycle checkpoints and apoptosis, also contributes to skeletal muscle differentiation in cultured cells.  It does not, however, induce myogenesis.  We and others propose that p53 acts as a backup for MyoD.  A corollary to this proposition is that p53 and MyoD must have some activities in common.  Several such activities have already been identified.  A specific aim for my study, in collaboration with a second student, is to identify a suite of genome-wide regulatory activities shared by p53 and MyoD in cultured cells.  In addition, I will determine whether or not p53 facilitates myogenesis initiated by MyoD in our cell culture system, as it has been shown to do in other

Poster #6-Benjamin Bush

An assessment of the Building Block Hypothesis as Applied to the Automatic Generation of a LOGO Command Sequence for the
Turtle Based Reproduction of a Line Drawing

Benjamin J. Bush1 and Todd Ebert, Ph.D.2
1Department of Mathematics and Statistics, California State University, Long Beach, Long Beach, CA 90840
2Department of Computer Engineering and Computer Science, California State University, Long Beach, Long Beach, CA 90840Inspired by genetics and natural selection, evolutionary algorithms are used to solve difficult optimization problems, particularly in the field of engineering. I investigated the problem of generating a command sequence that will allow a small robot (the LOGO Turtle) to reproduce a human-made line drawing. In the algorithm, a starting population of command sequences is generated. A fitness value, which represents how closely the drawing generated by a given command sequence resembles the human-made drawing, is assigned to each individual. Highly fit individuals are then selected for reproduction, thus generating the next generation of command sequences. Holland's Building Block Hypothesis suggests that the best form of reproduction is "single point crossover", which is analogous to the chromosomal crossover that occurs within eukaryotic cells. However, the No Free Lunch Theorem, proved by Wolpert and Macready, definitively shows that this cannot always be the case: There are some optimization problems in which the Building Block Hypothesis can be applied, and others in which it is inappropriate. By comparing the performance of different types of "sexual reproduction," I was able to show the existence of "highly fit" partial solutions (building blocks) within the search space of my problem. Empirical analysis yields the conclusion that reproduction schemes which preserve building blocks perform better on this particular optimization problem than reproduction schemes that are likely to either destroy building blocks or not incorporate them at all. My results contribute the growing body of empirical research regarding the function of sexual reproduction, both in engineering as well as in biology.This project is supported by the Louis Stokes Alliance for Minority Participation (NSF grant HRD #0331537) and the CSU Chancellor's Office. top


Poster #7- Deisy Contreras

Flouroquinolone Resistance Determinants in Clinical Isolates
of Acinetobacter baumannii

The emergence of multidrug resistance in different bacterial strains has placed great importance in the discovery of new antimicrobial agents. This increasing level of resistance has provoked a great deal of alarm in the public health sector world-wide.  There has been a global concern of the ever evolving pathogenic Acinetobacter baumannii. This minute form of life has been rapidly evolving through the years into one of today’s most potent opportunistic pathogen. Acinetobacter baumannii plays a significant role in the rising cases of nosocomial infections in hospitals around the world.  Thus, there is an urgent unmet medical need to discover and develop novel antibiotics to combat infections caused by these multidrug resistant pathogens.  Previous results in the Xu Lab have demonstrated that all 20 clinical isolates from Los Angeles County and 8 New York strains of Acinetobacter baumannii were resistant to ciprofloxacin. The overall objective of this study is to determine the molecular basis of ciprofloxacin resistance in these strains.  We believe that the primary mechanism of ciprofloxacin resistance is due to drug target (gyrA and parC) structural changes due to point mutations in these genes.  For DNA gyrase subunit-A, there is a focus on the following amino acid sequences: Gly-81 (GGT), Ser-83 (TCA), Ala-84 (GCT) and Glu-87 (GAA).  With regards to DNA topoisomerase IV subunit-C, there are 2 major sites of point mutations altering the amino acids: Ser-80 (TCG) and Glu-84 (GAA).  To test our hypothesis, ciprofloxacin susceptibility of selected clinical isolates from Greater Los Angeles, New York City and France will be determined.  For ciprofloxacin-resistant strains, PCR amplification of gyrA and parC genes, followed by DNA sequencing will be performed to determine the gene sequences of gyrA and parC which might be implicated in the ciprofloxacin resistance.  Results obtained have shown that 19 of the clinical isolates from Los Angeles County, and all of the New York City and France isolates have exhibited point mutations on the Ser-83 (TCA) sequence of the gyrA gene.  Sequencing of the parC genes from the 20 clinical isolates from Los Angeles County have shown that there is always one point mutation that exists in the codon for either Ser-80 (TCG) or Glu-84 (GAA).


Poster #8-Karla Banos

Karla G. Banos & Ray De Leon

Spinal cord injury (SCI) is damage to the spinal cord that produces motor and sensory deficits. In contrast to peripheral nerves, central nerve axons do not regenerate. The partial recovery seen after a spinal cord injury might be due to reduction of spinal shock and rewiring of new and old synapses following sprouting. Many studies of plasticity following spinal cord injury in animal models have focused on the corticospinal tract (CST) because of their major roles in controlling fine motor movements and reticulospinal tracts for their contribution in locomotor function. After SCI, the spinal cord is capable of forming collateral sprouting dorsal and rostral to the lesion. The brain is also capable of compensating for the loss of motor and sensory dysfunction by reorganizing neural pathways based on new experiences. The goal of my study is to not only look at plasticity in the brain and spinal cord after the axotomy of sensory and motor tracts, but also how short-term exercise and an enriched environment improves this recovery. My hypothesis is that the rats that receive robotic-assisted treadmill training and are housed in an enriched environment will undergo a greater degree of plasticity in the spinal cord and brain after spinal cord injury compared to controls. The experiments in this project will help us better understand how prolonged exercise after spinal cord injury influences the body’s natural compensation for the loss of functions. By better understanding this process, we will be able to look at ways to enhance natural recovery after SCI.
Poster #9- Xiomara Madero

Isolation and characterization of the
luciferase protein of the ostracode Vargula tsujii

Various species of cypridinid ostracods, such as Vargula tsujii, exhibit the ability to bioluminesce. Vargula tsujii is a small, about 3 mm long, nocturnal ostracod crustacean. It lives in sand at the bottom of shallow marine waters off the coast of California and Baja California, and becomes an active feeder in the water column at night. When disturbed, it secretes luciferin and luciferase into the seawater producing a bright luminous cloud of blue light (465 nm). Bioluminescence occurs due to the interaction of the luciferase enzyme with the luciferin substrate.  This ability to bioluminesce allows for the use of luciferase as a reporter gene in reporter assay studies. The objective of this research is to isolate and sequence the V. tsuji luciferase protein. With this information, an oligonucleotide probe will be designed, facilitating isolation and sequencing of the V. tsujii luciferase cDNA. The sequencing of the cDNA of V. tsujii luciferase will allow for the creation of another reporter gene as well as the use of the sequences for interspecies comparisons to study the evolution of luciferase in cypridinid ostracods. top

Poster #10- Mesfin Gewe

Study of the Functional Redundancy between the Myogenic Regulatory Factor, MyoD and Tumor Suppressor, p53 using Gene Expression Array Analysis
Mesfin Gewe and Sandra B. Sharp     

Muscle development is dictated by members of the tissue specific myogenesis regulatory factor (MRF) family, which in mammals and birds includes Myf-5, MyoD, myogenin and MRF-4. In addition to the MRFs, generally expressed regulatory factors, such as tumor suppressor p53, play a significant role in the successful differentiation of muscle cells. Results from cell culture experiments indicate that p53 contributes to the completion of myogenesis, but this contribution is not readily apparent in whole mouse p53 gene knockouts.  One possible explanation for this is that in cell culture conditions, which are suboptimal relative to in vivo conditions, p53 functions as a backup.  This function might be apparent under in vivo conditions but only if both p53 and the molecule for which it is backing up in culture were absent.  Known indications of functional redundancy between p53 and MyoD include cell cycle arrest, up-regulation of Rb and p21, and cooperation between MyoD and p53 in the expression of muscle creatine kinase. The objective for this study is to identify additional functional redundancies by using global gene expression analysis to compare the genes that are expressed or repressed when p53 is expressed in the absence of MyoD and vise versa, using congenic cell lines that express either p53 or MyoD from a transgene in a p53 and MyoD “null” background.  Balb 10(1), cells which are known to be non-myogenic and p53 null will be used to derive the cell lines required for the experiment.  In the case of the p53-expressing line, a p53 cDNA will be driven by a zinc inducible promoter that has been amplified for cloning purposes from the mouse genome using PCR techniques.  Whether or not p53 plays a role in myogenesis in vivo, the work we propose is significant because it has the potential of identifying additional pathways that are important for myogenesis.

Poster #11- Omar Moreno
Measurement of the Analyzing Power of CH2 via the Recoil Polarization
Technique to Q2 = 9 GeV2 at the Thomas Jefferson
National Accelerator Facility

Omar Moreno
Dr. Konrad Aniol, Dr. Marty Epstein, Dr. Dimitri Margaziotis
It is the goal of nuclear physics to understand matter at its most fundamental level.
However, a great mystery still surrounds even the most familiar of particles such as the pro- ton and neutron. In the late 1920’s the properties of such particles were thought to be well understood if they were assumed to be fundamental. However, experimental discrepancies shifted the notion of the fundamental ideal of these particles towards a model which gave them structure. The idea was that these hadrons were actually composed of three funda- mental particles known as quarks which interact through the exchange of gluons. This led to the development of Quantum Chromodynamics (QCD) in the 1970’s. The goal of the GpE -III experiment is to provide data for either verification or elimination of some current QCD models. This will be done by measuring the charge and current distributions of the quarks within the proton using the recoil polarization technique up to a value of Q2 = 9 GeV2 . In the process, the analyzing power of CH2 will be extracted for the highest Q2 value in order to shed light on the mysteries of the strong interaction.

Poster #12-Cinthya Ramirez

Career Identity Formation among Latino College Students

Jessica M. Dennis, Jean S. Phinney, Angelica Lopez,
| Delia M. Guitierrez, Cinthya Ramirez, Sonsoles Calderon

Career identity is important to identity formation.  Research has found that youth from working class backgrounds face different career identity challenges.  The current study sought to identify development in Latino college students.  55 Latino college students (43 women & 12 men) participated in a structured career identity interview and were assigned to a career identity status (achieved, moratorium, foreclosed, diffuse).  Those who were achieved reported the most support.  Those in moratorium were most likely to mention someone who inspired them in their career.  Those in diffusion were most likely to report being discouraged by obstacles they faced.  The context that most facilitates career exploration is one in which supportive individuals are available to provide help, motivation, and inspiration.


Poster #13- Maritza Hernandez

Title: Enzyme Kinetics of Plasma Lipoprotein Cholesterol
Metabolism in Jojoba Oil-Fed Rabbits

Authors: Maritza Hernandez and Raymond E. Garcia

Dietary cholesterol lowers high-density lipoprotein cholesterol concentration [HDL-C] in New Zealand White (NZW) Rabbits. This is correlated to a greater risk of developing cardiovascular diseases (CVD). However, when jojoba oil is supplemented to the cholesterol-rich diet, [HDL-C] remains normal, which lowers CVD susceptibility. Our objective is to determine the mechanism by which dietary jojoba oil alters HDL-C metabolism in cholesterol-fed rabbits. It is our hypothesis that dietary jojoba oil inhibits cholesteryl ester transfer protein (CETP) and activates lecithin:cholesterol acyltransferase (LCAT). To test this hypothesis, NZW rabbits were fed either a normal (N), 3% jojoba oil (J), 1% cholesterol (C), or 1% cholesterol + 3% jojoba oil diet. Blood sera were then collected at 0 and 7 days to be analyzed. CETP rate was determined via a fluorometric assay and the rate of LCAT was found by measuring the loss of FC over time. CETP activity was slightly lower in CJ-fed rabbits than in C-fed rabbits, but both had a greater CETP activity than the N- and J-fed rabbits. Cholesterol and jojoba oil have an additive effect on the activation of LCAT. In conclusion, dietary jojoba oil inhibits CETP and activates LCAT in the presence of dietary cholesterol. (BIOMED PREP Grant Number: GM064105)

Poster #14- Carlos Hernandez

Increasing the rigidity on resorcin[4]arene based capsules


The field of self-assembled molecular capsules, via covalent interactions, has become very important in the development of “molecular devices” to form a structure with an internal cavity capable of hosting guest molecules.


Poster #15-


Poster #16-



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