Abstract Resources

Mechanism of Action of Antifungal Peptoids

Janna Abou-Rahma
Faculty Mentor: Dr. Kevin Bicker
Middle Tennessee State University

Mechanism of Action of Antifungal Peptoids Due to the rise of drug resistant strains of fungal pathogens such as Cryptococcus neoformans and Candida albicans, there has been a need to identify new antifungal agents. In comparison to naturally produced antifungal peptides, antifungal peptoids mainly differ in structure, which prevents protease recognition giving higher bioavailability. Previous studies have shown that peptoids are effective fungicides. RMG8-8 and RMG9-11, two peptoids recently discovered in the Bicker Lab, have proven to be effective antifungal agents against C. neoformans and C. albicans, respectively. Reported here will be studies to determine the mechanism of action and other vital therapeutic properties of RMG8-8 and RMG9-11 using various biochemical and microbiological assays. Preliminary results of critical micelle concentration testing indicate that RMG8-8 as well as RMG9-11 do not exist as micelles at their minimum inhibitory concentrations, but rather function unimolecularly. Using a parallel artificial membrane permeability assay, it was found that RMG8-8 is likely unable to penetrate the blood brain barrier. However, RMG9-11 demonstrated good permeability, indicating that it may be able to penetrate the blood brain barrier to treat dangerous neurological infections of fungi. Subsequently, assays will be conducted in order to further understand the mechanism of action of both peptoid compounds to address the rising concern of drug resistant strains of fungal pathogens.

Characterization of Antifungal Peptoid Dendrimers

Matthew Johnson
Faculty Mentor: Dr. Kevin Bicker
Middle Tennessee State University

Currently the rate of fungal infections across the globe is increasing and given increasing rates of resistance to a limited number of treatment options, new anti-fungal agents are desperately needed. Opportunistic fungi such as Cryptococcus neoformans are a major part of the problem, as they infect immunocompromised individuals. A vast majority of the antifungals on the market exhibit a variety of toxicities as well as drug interactions that prevent symbiotic treatment modalities. Peptoids are peptidomimetics that are N-substituted glycine oligomers, and have shown to have promise as antimicrobial agents due to their proteolytic stability, low hemolytic activity, quick killing kinetics, minimal mammalian toxicity, and nonspecific mode of action. Given this, our group has developed a promising antifungal peptoid (RMG8-8) for treatment of C. neoformans and to attempt to improve the activity of this molecule, we have explored a novel display of RMG8-8: peptoid dendrimers. Antimicrobial peptide (AMP) dendrimers have been reported to have hyper-potency against a wide variety of yeasts and their pharmacokinetics are improved due to increased steric hindrance, providing in vivo stability. Due to similarities between peptides and peptoids, these benefits are likely to apply to peptoid dendrimers. Specifically, several generations of RMG8-8 dendrimers have been synthesized displaying varying copies of the peptoid and will be tested for antifungal activity and mammalian cytotoxicity. This provides a promising therapeutic avenue to be explored.

Investigation of the Anti-viral Properties of Chlorine Dioxide Gas using the MS2 Bacteriophage

Hunter Brady
Faculty Mentor: Dr. Anthony Newsome
Middle Tennessee State University

Since the emergence of the SARS-CoV-2 virus, the etiological agent that causes COVID-19, the need to identify antiviral agents for disinfection purposes has dramatically increased. Chlorine dioxide gas has previously been identified as an antibacterial agent with strong oxidizing capabilities. The MS-2 bacteriophage has previously been identified as a suitable surrogate for the development and application of virucide decontamination methods by the Environmental Protection Agency. This study aimed to identify and assess the antiviral properties of chlorine dioxide gas and to identify optimum physical conditions for potential deployment in support of current antiviral disinfection needs. Using the MS-2 bacteriophage model system, preliminary studies used the double-layer agar plaque assay technique to evaluate the antiviral activity of chlorine dioxide gas. Results revealed up to a six-log (99.9999%) reduction of the MS-2 bacteriophage off of porous surfaces. These results suggest that chlorine dioxide gas is a suitable antiviral agent.

Antibiotic Resistance eDNA in the Stones River Watershed

Lacon Parton
Faculty Mentor: Dr. Rebecca Seipelt-Thiemann
Middle Tennessee State University

From the beginning of antibiotic use, antibiotic resistance with associated complications has been sweeping the nation. While bacteria can evolve antibiotic resistant genes by repeated exposures, they can also acquire existing genes encoding antibiotic resistance proteins by taking up environmental DNA fragments that originate from dead antibiotic-resistant bacteria present in the environment. Alternatively, bacterial viruses can carry antibiotic resistant genes which could transfer the resistance through infection. It is important to identify and track valid, local sources of antibiotic resistance genes in the environment as they represent not only presence of resistance, but a source of acquiring resistance. The purpose of this study is to track four β lactamase antibiotic resistant gene alleles (Bla-1, Bla-TEM, Bla-SHV, and BlaCTX) in the Stones River Watershed and compare the prevalence to land uses that are known to utilize antibiotics such as hospitals, veterinary clinics, and urban/agricultural sites. Environmental DNA will be isolated from obtained soil samples. These soil samples will be further cleaned in preparation to perform polymerase chain reaction followed by agarose gel electrophoresis which will determine the presence of the variants of the β-lactamase antibiotic resistance genes. A comparison of antibiotic resistance gene allele presence/absence with land use will reveal if any particular land use should be prioritized in the local battle against antibiotic resistance bacteria.

Investigating the Significance of the N-MYC-WDR5 Interaction in Pediatric Neuroblastoma

Jesse D. Scobee
Faculty Mentor: Dr. April Weissmiller
Middle Tennessee State University

Neuroblastoma (NB) is the most common solid-tumor pediatric cancer, and high-risk cases associated with N-MYC amplification show a 50% 5-year survival rate. N-MYC is an oncoprotein transcription factor that causes the transformation of a healthy cell into a tumor cell, and thus functional inhibition of N-MYC is a sought-after therapeutic goal. Recently, the chromatin regulator WDR5 was discovered as an important MYC co-factor that can modulate MYC target gene expression, and evidence in N-MYC amplified NB cell lines shows extensive co-localization of N-MYC and WDR5 at genes involved in multiple important biological functions. These data suggest that the N-MYC-WDR5 interaction may control a variety of important N-MYC related functions, however a clear analysis focused on any single function individually is currently lacking. Thus, this study was designed to determine if blocking the N-MYC-WDR5 interaction alters expression of genes linked to apoptosis, a well-studied function of N-MYC. Using multiple engineered NB cell lines, we performed mRNA analysis of pro- and anti-apoptotic gene expression. Interestingly, results of this study reveal that blocking the N-MYC-WDR5 interaction does not cause overt changes in apoptotic gene expression, suggesting that blocking the N-MYC-WDR5 interaction may not be sufficient to induce apoptosis. However, future studies using different cell lines or alternative methods may be useful to confirm these results. Given the extent of N-MYC and WDR5 co-binding at genes involved in essential biological processes, future investigation is warranted to deduce the totality of cellular consequences that occur when WDR5 cannot bind N-MYC in these deadly malignancies.

Analyzing the Ability of Astragalus tennesseensis to Accumulate Selenium

Yaseen Ginnab
Faculty Mentor: Dr. Frank Bailey
Middle Tennessee State University

Selenium is a metalloid and an essential micronutrient but is toxic in high amounts (Conrad and Moxon, 1980). This element is naturally occurring in many soils and can be accumulated by some plants. When accumulated in high amounts, generally considered to be above 1000 ug/g dry weight, the plant becomes toxic if eaten by animals and is called a selenium hyperaccumulator. A study by Ohlendorf et. al. showed that a diet high in selenium given to aquatic birds resulted in severe and fatal birth defects, often involving developmental deformities of various organs and external body parts (1986). Plants that can accumulate selenium do so by replacing sulfur with selenium in the amino acids within their tissues (Galston, 1981). Astragalus is one of the largest genera of plants, with estimations of around 3000 species. This genus is known to have many selenium hyperaccumulators; among these, one of the most well-studied species is Astragalus bisulcatus, which is often used as an indicator plant to detect seleniferous soils. Astragalus tennesseensis grows in Tennessee and surrounding states and is often found in Middle Tennessee’s unique cedar glades. The environments this species typically grows in contain low amounts of selenium, compared to A. bisulcatus growing in the western United States in highly seleniferous soils (USGS, 2008). This study aims to investigate whether A. tennesseensis can accumulate selenium. This species will be grown alongside A. bisulcatus to compare their reactions to varying levels of selenium treatment (0 mg selenium/kg dry soil, 1 mg/kg, 10 mg/kg, and 100 mg/kg). Sodium selenate (Na2SeO4) will be used for treatment. After treatment has been completed, the plants will be digested in nitric acid and analyzed by atomic absorption spectrophotometry to determine the selenium content (Bailey et. al., 1995).

Development of Monodispersed, Size-Discrete PLGA Nanoparticles for Uterine-Targeted Drug

Emaa Elrayah
Faculty Mentor: Dr. Jennifer Herington
Middle Tennessee State University

Preterm birth (PTB) is the leading cause of infant mortality, yet there are no effective treatments. Current tocolytics have poor specificity and readily cross the placental barrier, causing harm to both mother and fetus. Uterine-targeted nanoparticles have emerged as a potential drug-delivery system for the treatment of PTB. Poly(lactic-co-glycolic) acid (PLGA) is an FDA-approved biomaterial with the capacity for use in obstetric therapies. Due to the size-exclusivity of the placental barrier, the design of drug-encapsulated nanoparticles must consider particle size. Here we show the development of a procedure to formulate monodispersed PLGA nanoparticles with discrete size populations. Using an oil-in-water emulsion technique adapted from Haycook, et al (2020), we compared two different methods using either ethyl acetate (EtAc) or dichloromethane (DCM) as the organic phase. Furthermore, we tested different homogenization methods. We then developed a purification method using serial centrifugation to isolate discrete size ranges. The nanoparticles were analyzed for size and polydispersity via dynamic light scattering and verified via scanning electron microscopy. We found that the DCM formulation produced particles with a lower polydispersity index (PDI) than EtAc (0.20199 +/- 0.07 vs. 0.3037 +/- 0.03). We determined that homogenizing the emulsion at 45 seconds produced the most discrete size populations, with low PDIs (0.0813 +/- 0.0441). Here we show that we successfully employed a bench-top emulsion to create and isolate PLGA nanoparticles within specific size ranges. This approach holds strong potential for the development of a nanoparticle drug delivery system for PTB, for which novel therapies are desperately needed.

Investigating Parameter Estimation and Tracking Functions Used in the Confirmation of Autonomous Vehicle Radar Detection 

Jonathan Duke
Faculty Mentor: Dr. Jorge Vargas
Middle Tennessee State University

Autonomous vehicles are required to perform in a variety of weather conditions to ensure the safety of the consumers. RADAR sensors tend to be a cost effective and reliable route for automotive engineers because they perform well in a variety of weather conditions. RADAR is an acronym for Radio Detection and Ranging. RADAR works by using an antenna to emit and receive electromagnetic waves. When the antenna emits a signal, the power of that signal is completely dissipated into the environment. The electromagnetic waves then return to the receiver after it undergoes multipath propagation. Based on the environment surrounding the sensor, the electromagnetic wave will undergo change in either frequency or intensity. The receiver can provide information about the environment when compared to the emitted signal. There are several ways that these electromagnetic waves can be emitted and received, and it is one of the defining characteristics of a RADAR system. To explain further, Pulse RADAR measures the change in signal strength to calculate distance while Continuous RADAR uses the difference in frequency of the signals to calculate distance. Currently, one of the downsides with RADAR sensors is that their performance lowers in high traffic areas, meaning more false detections are made. Detections must be assigned to an object and class to make safe driving decisions without the input of the consumer. Once these detections are recognized and classified, they can be stored, discarded, or maintained depending on the parameter estimation and trackingfunctions. Improving the quality of RADAR detections allows for less false detections to be made, allowing for a safer driving experience for the consumer.

Effect of Acute Oxytocin Administration on Social Behavior in Male and Female Mice

Marzea Akter
Faculty Mentor: Dr. Tiffany Rogers
Middle Tennessee State University

Oxytocin is a neurotransmitter and hormone with a well-established role in prosocial behaviors in animals and humans. It is currently being tested in clinical trials for the treatment of social symptoms associated with autism spectrum disorders. However, the behavioral effects of oxytocin treatment have been variable with both prosocial (increased empathy) and antisocial (increased competitiveness) behaviors resulting in humans. Previous studies in our lab have shown increased anxiety-like behaviors in mice treated chronically with oxytocin (1 12 ug dose per day for 14 consecutive days, data unpublished). The current study aims to see the effect of acute oxytocin administration on social behavior in male and female mice to determine if the schedule of oxytocin administration affects behavioral outcomes. Adult C57BL/6J mice will be acutely pretreated with saline or oxytocin (12 ug) an hour before the behavior tests. Saline or oxytocin will be administered either intranasally (i.n., 12 ug in 12 uL, 6 uL per nostril) or intraperitoneally (i.p., 12 ug in 120uL). Mice will complete a battery of behavioral tests including the elevated plus maze (EPM), three-chamber sociability task (3C), and free dyadic social interaction (FDSI) after drug administration to determine changes in social behavior and anxiety-like behavior. Noldus EthoVision XT and human coders will code anxiety-like behaviors, social preference, and social novelty. I expect to find that acute oxytocin administration will increase sociability as measured by the 3C and FDSI tasks while avoiding increases in anxiety-like behaviors, as measured by the EPM task, associated with chronic administration.

Creation of Electro-Magnetic Assisted “Star-like” Formation From Cancer Cells Using a Laser Trap

Lindsey Tran
Faculty Mentor: Dr. Daniel Erenso
Middle Tennessee State University

Cancer is the second leading cause of death among humans worldwide. Although radiation therapy has been the most effective course of treatment for cancer patients, it still has harmful and long-lasting damages on their bodies, ruining their quality of life. The initial purpose of this study was to minimize radiation damage caused from cancer treatment by finding the minimal amount of ionization required to eliminate a single BT20 breast cancer cell, using laser-trapping (LT) technology. However, amid experimentation, the discovery of two scientific phenomena was made and given the titles “Dark-space” formation and “Star-like” formation. Both phenomena have shown the ability to rapidly absorb and conserve energy. With the world’s continuing advancements in technology, these two discoveries can be used as an approach to improve microchip technology and solar energy harvesting. Thus, the purpose of this research was expanded and separated into 3 phases: Single ionization, “Dark-space” formation, and “Star-like” formation. A 3:1 mixture solution of BT20 cancer cells and magnetic beads was poured onto a depression slide and placed onto the laser trap. For over 4 years, the same depression slide has been used to conduct measurements for each phase. In the single ionization phase, magnetic beads were used to minimize the amount of ionization required to eliminate a singular BT20 cell. It was found that the interaction between the laser’s radiation energy and the magnetic beads’ electromagnetism accelerated the rate of ionization. Thus, a significant reduction of approximately 83% was observed in the ionization period with the addition of the magnetic beads. Further on to Phase 2, a “Dark-space” forms once the mixture interacts with the laser trap and acts as an energy storage capacitor that rapidly expands as the increasing amount of radiation energy is absorbed. This expansion causes all surrounding matter to accelerate towards the dark region, yet it is never able to penetrate the space. Upon explosion, the energy of “Dark-space” causes the surrounding matter to form into a plasma, acting as a sea of positive and negative charges. Leading into Phase 3, a “Star-like” illumination forms once the plasma interacts with the laser trap. This interaction causes an emission of intense blackbody radiation that grows and becomes more robust as more energy is absorbed. Overall, applications of this study can provide improvements in cancer treatment, microchip technology, and solar energy harvesting.

S-Invertibility of Unicyclic and Bicyclic Graphs

Isaiah Osborne
Faculty Mentor: Dr. Dong Ye
Middle Tennessee State University

A graph is an abstract mathematical model of a network, which has vertices and edges connecting vertices. Graphs can be used to model many networks, such as the internet, social networks, and molecules. For example, if a vertex represents an atom and an edge represents the bond between two atoms, then a graph can represent a skeleton of a molecule; if a vertex represents a person and an edge represents a relation between two persons, then a graph can be used to represent a social network. Graphs can be represented mathematically using matrices, for example, the adjacency matrix of a graph with n vertices is an (n × n)-matrix whose ij-entry is the number of edges connecting the vertex i and the vertex j. A graph is invertible if its adjacency matrix is invertible, and a graph is considered s-invertible if its adjacency matrix is invertible and its inverse is a matrix with each entry belonging to {−1, 0, 1}. While the concept of s-invertibility was introduced in the 1980’s, there has been very little progress toward characterizing s-invertibility of graphs. Buckley, Doty and Harary characterized s-invertible trees in 1988, and Kalita and Sarma characterized a sub-family of unicyclic graphs in 2021. In our research, we characterize s-invertible graphs based on feasible paths that are defined as paths whose vertex-removal results in a subgraph with a 2-matching. This characterization provides a tool for us to completely determine the family of s-invertible graphs with at most two cycles, which extends the results of Buckley-Doty-Harary for acyclic graphs and Kalita-Sarma for a sub-family of unicyclic graphs.