Abstract Submitted for Presentation

Alterations of dendritic spines in hiv associated neurocognitive disorders  

Infection by the Human Immunodeficiency Virus (HIV) alters not only the immune system, but also the Central Nervous System (CNS).  Invasion of the CNS by HIV-1 can cause HIV-associated neurocognitive disorders (HAND) and damage is usually observed through non-apoptotic pathways. One prominent pathway is synaptodendritic injury, which compromises the ability of neurons to communicate with each other; however, the mechanisms involved in neuronal injury are still unclear. Previous studies from our lab show that the HIV-1 envelope protein, gp120, increases neuronal expression of the protein ferritin heavy chain (FHC), a novel negative regulator of chemokine receptors function. Specifically, FHC disrupts the CXCL12/CXCR4 chemokine/receptor axis, a signaling pathway involved in CNS development as well as in the regulation of important functions of the adult brain, such as neurotransmission and cell differentiation. Our previous studies also demonstrated that the CXCL12/CXCR4 pair contributes to spine homeostasis and changes in FHC are involved in HIV neuropathology.             In this study, we focus on alterations caused by HIV-1 proteins in the dendritic arbor of pyramidal neurons in different areas of the rat cerebral cortex. We investigated the effect of isolated envelope proteins, namely gp120, or multiple proteins. The two animal models used for this purpose are adult Sprague Dawley (SD) rats treated with gp120IIIB and Fisher 344 (F344) HIV-Tg rats, which express 7 of the 9 HIV genes.   Controls groups were vehicle-treated SD and F344 wild type rats, respectively. Either Golgi stain or diolistic labeling was used to visualize neurons in brain cortex sections of the experimental and control group animals. The Neurolucida software was used for tracing and 3D reconstruction of imaged neurons. Both dendritic spine density and morphology were examined in the prefrontal, motor, and somatosensory cortex of each animal group. Furthermore, behavioral studies were conducted to determine cognitive deficits caused by the viral proteins in the two animal models. In previous studies we had found that HIV can cause reduction in spine density of pyramidal neurons in layer II/III of the prefrontal cortex. The objective of the present study was twofold: a) to correlate the observed dendritic changes with the ability to learn new tasks, and b) to investigate whether injury is limited to layer II/III of the prefrontal cortex. Our results show a reduction in spine density in the motor cortex, and no significant difference in spine density in the somatosensory cortex in both models. Morphological alterations were observed in all 3 regions, including the prefrontal cortex, with a shift towards an immature spine type found in both HIV animal models. Slight differences were detected between brain areas and rodent models. These results demonstrate that alterations are not limited to the prefrontal cortex and highlight the variable regional susceptibility of neurons to the damage induced by HIV proteins and inflammation, which may underlie the cognitive and behavioral symptoms observed in patients. Furthermore, the shift towards immature spine morphology in our two animal models of HAND suggests that these neurons may not be able to sequester incoming excitatory neurotransmission in a regulated fashion, leading to neuronal injury and dysfunction.

Event: DUCoM Discovery Day 2013
Title: Requirement of alcohol dehydrogenase-related genes for preventing DNA damage
Type of Presentation: Poster
Abstract:

Acetaldehyde, the primary metabolite of alcohol, plays a major role in alcohol-related esophageal cancer. Acetaldehyde is a possible carcinogen because it crosslinks proteins with DNA and disrupts the DNA replication process, causing DNA damage and genomic instability. In addition, acetaldehyde is also responsible for causing the symptoms of a “hangover.” Alcohol consumption leads to a buildup of acetaldehyde in the body. Humans possess genes specialized for the detoxification of this harmful chemical into harmless acetic acid (vinegar). However, approximately fifty percent of the East Asian population has a variant of the acetaldehyde dehydrogenase gene ALDH2, and is unable to efficiently metabolize acetaldehyde to acetic acid. The result is an “alcohol flush reaction,” or reddening of the face due to capillary dilation, as well as increased risks of esophageal and intestinal cancers. Using the fission yeast Schizosaccharomyces pombe as a model organism, we have characterized genes crucial for the dehydration of alcohol-related substances. Serial dilution growth assays were conducted to assess alcohol or aldehyde sensitivity of different alcohol or aldehyde dehydrogenase mutants. Work is ongoing to further investigate how these mutations affect cellular processes related to genome maintenance mechanisms, including DNA protection, DNA repair, and cell cycle checkpoint control.

Birds as vectors for Borrelia burgdorferi  
Emily N. Ostrow1 and Jason D. Weckstein1
1Department of Biodiversity, Earth, and Environmental Sciences and Academy of Natural Sciences of Drexel University, Ornithology Department, Philadelphia, Pennsylvania, United States of America  

Lyme Disease is the most prevalent vector borne disease in North America. It is caused by the bacteria Borrelia burgdorferi s.l., which has a complex life history involving a tick vector and vertebrate host. Recent work on the population genetics of the tick vector Ixodes scapularis and Borrelia burgdorferi indicates that their genetic population structures do not match. The tick Ixodes scapularis has structured populations indicating little movement across geographic space, whereas the bacterium Borrelia burgdorferi has little structure indicating greater movement across geographic space, suggesting that the ticks are not the primary dispersers of the pathogen across geography. Therefore, one of the vertebrate hosts is likely more important than the tick vector in determining the population structure of Borrelia. I am analyzing birds as a potential long distance dispersal agent for Borrelia. Many migratory bird species travel thousands of miles, twice annually, and are known to act as hosts for larval and nymphal Ixodes ticks. I will screen ~3000 individuals with tissue and blood samples collected from migrant birds in Chicago, Illinois and in Chester and Bucks counties, Pennsylvania. I am extracting DNA from these tissues and using a nested polymerase chain reaction (PCR) protocol and specific primers to screen for DNA from the 5S-23S intergenic spacer region of the Borrelia genome. Positive amplifications indicate a Borrelia infection. I will sequence the products of all positive samples to characterize and identify the specific strains of Borrelia burgdorferi present. Preliminary results with approximately 200 local birds suggest that there is a high prevalence of Borrelia infecting birds in this region compared to other published results. In-depth analyses with these data will help us to understand variation in pathogen prevalence across regions (NE versus Midwestern US), across seasons (fall versus spring migration), and between host species. 

Interface behavior in La1−xSrxFeO3−δ /Nb:SrTiO3 perovskite oxide heterostructures CAROLINE (LIGE) ZHANG, MARK SCAFETTA, STEVEN MAY, Drexel University — We report the interfacial transport behavior in La1−xSrxFeO3−δ /Nb:SrTiO3 perovskite oxide heterostructures. Strained epitaxial films were deposited on SrTiO3 and Nb:SrTiO3 substrates using oxide molecular beam epitaxy. Oxygen concentration was controlled by heating and re-annealing in a tube furnace with a mixture of O2 and O3. Temperature dependent currentvoltage (I-V) characteristics were measured from the junctions. From these I-V data, ideality factors for the heterojunctions were obtained. The ideality factors are found to be much larger than 1, indicating transport differs substantially compared to conventional semiconductor heterostructures. 

Presented research to Drexel faculties and students. Poster title: Interface Behavior in La1-xSrxFeO3-δ/Nb:SrTiO3 Perovskite Oxide Heterostructures

Hematite (α-Fe2O3) has been widely investigated as a promising material for
photoelectrochemical (PEC) water-splitting due to its abundance, stability, and favorable band 
gap of 2.1 eV, with a theoretical 15% solar-to-hydrogen efficiency. Despite these desirable 
properties, several challenges remain, including slow oxygen evolution reaction (OER) kinetics 
and a mismatch between absorption depth and minority carrier collection length. Due to this
mismatch, nanostructured architectures are necessary to achieve large photocurrents.
 Photoanodes of hematite-coated nanostructured scaffolds and thin films on F:SnO2 (FTO) 
glass substrates were fabricated to investigate the effects of film thickness, interfaces, metallic 
dopants, and nanostructured architecture on PEC water splitting. Hematite thin films were 
fabricated by successive ionic layer adsorption and reaction (SILAR), where a substrate is 
alternately immersed in iron-containing and oxidizing baths for a 0.5 nm growth rate per SILAR 
cycle. Annealing at 775oC caused phase-transformation from iron-hydroxide to hematite and 
diffusion of Sn from the FTO substrate into the hematite, which may increase film conductivity 
and enhance OER kinetics.
 Photocurrent increased with film thickness from heightened light absorption but 
approached saturation at about 120 cycles due to charge collection limitations. Photocurrent was 
further enhanced by adding an ultrathin (<10 nm) TiO2 interlayer between the FTO and hematite, 
which likely improves the interface and reduces shunting. Depth-profiled XPS reveals that both 
Ti and Sn diffuse through the hematite upon annealing. The surface is particularly rich in Ti, 
which may passivate surface traps or catalyze OER kinetics.
 To increase light absorption while maintaining hematite thickness similar to the 
collection length, nanostructured inverse-opal Sb:SnO2 (ATO) scaffolds with hematite coatings 
were prepared. This scaffold increased surface area by 85% compared to planar films, and 
photocurrent increased by over 15%. Nanostructured architectures and interfacial treatments 
following this approach will increase efficiency of PEC water splitting with hematite.

  Embedded within a study on brain response to food was a comparison of subjective and objective measures of loss of control (LOC) over eating with actual food intake.  Post-hoc analysis of food consumption and scores on the LOCES (Loss of Control Eating Scale, a new subjective measure of LOC over eating) were compared within LOC groups defined by spontaneous self-report, or the Eating Disorder Examination-Questionnaire (EDE-Q), the diagnostic standard for assessment.  The sample was composed of 10 men and 8 women, all healthy with no psychopathology.  Based on spontaneous self-report grouping we observed significant differences in the EDE-Q global scores between lean control and obese control groups (p=0.018) and between obese control and obese LOC groups (p=0.043). There were also significant differences in LOCES scores between all groups (p < 0.001).  Based on EDE LOC grouping, there were significant differences in EDE global score (p = 0.04) and LOCES score (p = 0.055) between all groups.  Additionally, based on EDE-Q LOC grouping, there was a significant increase in preferred food intake in the obese LOC group compared to the other two groups (p = 0.045), after controlling for sex.  There was no difference in non-preferred food intake among any of the spontaneous self-report or EDE-Q LOC groups.  Our data demonstrates an association between objective LOC and subjective LOC as measured by the EDE-Q, but no association between objective and subjective LOC as measured by LOCES as reported by Latner et al (2014).          

I did more research wohoo

This is the abstract for my awesome cool research.

Despite efforts of the past three decades, participation of underrepresented minority groups is still an issue in STEM disciplines. Minority ethnic groups account for approximately 30% of the United States population, but only 9.1% of those working in STEM occupations[1, 2]. In this context, a program between the Community College of Philadelphia  and Drexel University to provide research experience to underrepresented minority students (UMS) was implemented based on the hypothesis that learning about science and engineering is more effective if it is paired with the challenge of independent research in a specifically collaborative “micro-environment”, as for example in active research laboratories. Six undergraduate UMS (three male, three female) were selected from a pool of twenty applicants in the inaugural year. Each student independently selected a Drexel faculty advisor and corresponding research group best aligned to their interests within the first two weeks of ten week program. From the outset, library integration underpinned the program. To this aim, students were personally introduced to key library professionals and digital library search tools and databases were immediately employed to review at least three relevant journal articles to their research foci, which assisted to form the basis for independent research proposals. By week four, students presented research plans before a panel of faculty and student judges. In order to complete the program, each student produced three final deliverables - an oral presentation, technical poster and paper describing their work. In addition, students were exposed to STEM research in an application-driven industrial setting through a visit to a private corporation known for its innovation. A final survey and individualized assessments were conducted to evaluate the effectiveness of the program and progress of the individual students, respectively. Students demonstrated familiarity with basic research methods and universally reported increased interest in STEM education and careers, with four continuing to work in their labs beyond the program’s formal duration. Beyond the summer research program, the partnership facilitated: (i) tutoring in community college STEM courses by Drexel graduate students, (ii) a STEM career discussion panel, and (iii) a discussion among faculty and staff from both institutions on addressing challenges UMS face in STEM education. Keywords—Research-based Learning, STEM education, Minority Participation References [1]        President's Council of Advisors on Science & Technology"Engage-to-Excel: Producing One Million Additional College Graduates with Degrees in Science,Technology, Engineering, and Mathematics," E. O. o. t. President, Ed., ed. Washington, D.C.: Executive Office of the President 2012. [2]        C. Vest, "The Image Problem for Engineering," The Bridge vol. 41, pp. 5-11, 2011.