Doctor of Philosophy, University of Toledo, 2017, Chemistry

Tuberculosis(TB) is a contagious disease caused by Mycobacterium tuberculosis (Mtb). According to the World Health Organization (WHO), TB resulted in the deaths of 1.8 million people from a total of 10.4 million infection cases in 2015. In order to eradicate the ongoing TB threat and combat multidrug-resistant strains (MDR-TB) new therapies are need. This dissertation covers the history of TB, Mtb cell wall structure, trehalose utilization pathways (TUP), and the design and synthesis of inhibitors related to targets in TUP; i.e. Glycosyl hydrolase GlgE, Antigen 85C (Ag85C), Pks13 and TPP2. The second chapter describes the design and synthesis of a molecular probe to investigate the active site topology of Streptomyces coelicolor (Sco) GlgEI, a model enzyme of Mtb GlgE. Mtb GlgE is an essential enzyme which catalyzes the synthesis of cytoplasmic a-glucan by transferring maltose-1-phosphate (M1P) to a growing alpha-1,4-glucan chain. 2-Deoxy-2,2-difluoro-alpha-maltosyl fluoride (alpha-MTF) was designed as a non-hydrolysable substrate mimic of M1P to probe the active site of GlgE1 without disruption of catalytic residues. The synthesis and challenges faced during preparation of alpha-MTF are briefly described in this chapter. The key reaction in the synthesis was the use of 1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane ditetrafluoroborate (Selectfluor), which was used to transform peracetylated 2-fluoro-maltal into peracetylated 2,2-difluoro-a-maltosyl fluoride and peracetylate 2-deoxy-2,2-difluoro-alpha-maltosyl fluoride in a single step. The resulting compound was used by the Ronning group and co-crystallized with the Sco GlgEI-V279S. The X-ray structure of the crystals identified key interactions which may be helpful in further drug design. The third chapter involves targeting Ag85C, in which we synthesized a library of 2-alkyl-1,2-benzisoselenazol-3(2H)-ones as potential covalent inhibitors. The synthesis used a novel thermal and photoinduced copper- (open full item for complete abstract)

Committee: Sucheck Steven Prof (Advisor); Donald Ronning Prof (Committee Member); Zhu Jianglong Dr (Committee Member); Tillekaratne Viranga Dr (Committee Member) Subjects: Chemistry; Organic Chemistry

Master of Science (MS), Bowling Green State University, 2021, Biological Sciences

An oomycete pathogen, Globisporangium ultimum (also known as Pythium ultimum), causes damping-off on a wide range of hosts. This disease is one of the major constraints on soybean production. Although fungicide seed treatments are often used to combat the disease, significant losses occur in cool and moist conditions. In addition, the emergence of fungicide-resistant isolates, the lack of resistant cultivars, and the ineffectiveness of crop rotations pose further challenges in managing the disease. Hence, new molecular targets are needed to control G. ultimum. In this study, G. ultimum and G. sylvaticum were isolated from the soybean fields (Bowling Green, Ohio). Pathogenicity assays were evaluated on two soybean cultivars: William and William 82. The seed-and seedling rot assays determined that both the isolates were pathogenic to both the seeds and seedlings of soybeans. Globisporangium ultimum showed a 100% disease severity index (DSI) on both cultivars, while G. sylvaticum had a DSI of 73.1% and 93% on William and William 82, respectively. The seedling root rot assay showed a similar rate of infection in both cultivars, based on the root surface area compared to the control (healthy plant). Kazal-type serine protease inhibitors (KPIs) are produced and secreted by many pathogens, including G. ultimum. They neutralize plant defense proteins in the protease family, allowing pathogens to colonize the hostile apoplast. In silico analysis via FungiDB showed that G. ultimum genome encodes 13 putative secreted KPIs. Four genes: PYU1_1G000142, PYU1_G009682, PYU1_G013310, and PYU1_G002778 were selected for gene expression analysis during infection using qPCR. Results showed that PYU1_1G000142 and PYU1_G009682 showed the highest expression at 48 hours post inoculation (hpi), indicating that they were associated with late infection in both soybean cultivars. In contrast, PYU1_G013310 showed highest expression at 6 hpi in William and at 24 hpi in William 82, indicating th (open full item for complete abstract)

Committee: Vipaporn Phuntumart Ph.D. (Advisor); Raymond Larsen Ph.D. (Committee Member); Paul Morris Ph.D. (Committee Member) Subjects: Agriculture; Bioinformatics; Biology; Molecular Biology

Doctor of Philosophy (PhD), Ohio University, 2019, Chemistry and Biochemistry (Arts and Sciences)

Tau protein plays a crucial role in stabilizing microtubules inside neuronal axons and maintaining the structural integrity of neurons. Binding of tau to microtubules at tau repeat domains (R) is regulated by phosphorylation. This phosphorylation is regulated by a family of enzymes called kinases. Under pathological conditions, tau is hyperphosphorylated by elevated activity of kinases such as the microtubule affinity-regulating kinase (MARK) proteins, leading to complete detachment of tau, microtubule collapse and ultimately, neuronal cell death. The free, hyper-phosphorylated tau proteins aggregate into insoluble prion-like oligomers which have been implicated in neurodegenerative diseases, including Alzheimer's disease (AD) and frontotemporal dementia. There is currently no treatment to prevent the progression of AD; all medications available today only reduce the symptoms of the disease. Moreover, using small molecule kinase inhibitors as treatment can cause serious negative side effects because of their lack of specificity. The research outlined in this work aims to develop a metabolically stable, selective peptide-based MARK kinase inhibitor that targets MARK proteins. This peptide-based inhibitor, designated tR1, was designed as a direct sequence memetic of the microtubule-binding R1 repeat domain of tau. Here, we show that tR1 peptides can inhibit MARK2 activity and reduce the level of tau phosphorylation in vitro and in cultured rat primary cortical neurons. In the second segment of this project, we attempted to inhibit tau aggregation in vitro using peptide-based aggregation inhibitors. Here, we synthesized peptides designated (an-R3, PHF6, and PHF6*) which mimic nucleating sites in the microtubule binding repeat domain of full-length tau. We hypothesized that these peptides would associate with tau protein and block further tau aggregation. We assessed the ability of these three peptides to inhibit tau aggregation using in vitro heparin-induced tau (open full item for complete abstract)

Committee: Justin Holub M. (Advisor); Marcia Kieliszewski (Committee Member); Robert Colvin (Committee Member); Jana Houser (Committee Member); Jixin Chen (Committee Member) Subjects: Biochemistry

Doctor of Philosophy, The Ohio State University, 2016, Pharmaceutical Sciences

Cancer has become a leading cause of death worldwide. With increased understanding of the mechanisms of cancer cell survival and progression, targeted cancer therapy has become a major approach for development of future cancer therapies. Here in this dissertation, we would like to present two approaches to develop next generation cancer drugs: the first is glucose transporter (GLUT) inhibitors and the second is HSP90 inhibitors. Cancer cells undergo metabolic reprogramming, called the Warburg effect, characterized by a shift to aerobic glycolysis. This metabolic difference between malignant cells and normal cells provides a therapeutic opportunity to inhibit cancer cell growth without harming normal cells. Previously in our lab, we identified a novel thiazolidinedione derivative, OSU-CG5, as a potent GLUT inhibitor to inhibit cancer cell proliferation. However, the in vivo efficacy of this compound did not correlate with the profound in vitro activity. In this study, we constructed a library of OSU-CG5 derivatives to search for more potent agents. CG-77 has been identified as the next generation GLUT inhibitor with the replacement of the phenol group with a sulfonamide group. This modification not only improved the in vitro activity in several cancer cell lines, but also the in vivo efficacy as demonstrated in a PC3 xenograft mouse model. Furthermore, we have shown that CG-77 is capable of inhibiting aberrant Wnt signaling pathway in colon cancer cells. Specifically, CG-77 inhibits the formation of ß-catenin/TCF4 complexes and thus inhibits the expression of oncogenic Wnt target proteins. These findings demonstrate the involvement of GLUT1 in the Wnt signaling pathway and provides a rationale for investigating its potential use for colorectal cancer therapy. The HSP90 chaperone is a key component in the protein maturation and stabilization process. There is a long history of the development of HSP90 inhibitors; however, none have been approved by the FDA so far. (open full item for complete abstract)

Committee: Ching-Shih Chen (Advisor); James R. Fuchs (Committee Member); Mark Mitton-Fry (Committee Member); Karl A. Werbovetz (Committee Member) Subjects: Biomedical Research; Organic Chemistry; Pharmacy Sciences

Honors Theses, Ohio Dominican University, 2015, Honors Theses

An experimental project regarding the synthesis of a new molecule and using it in development of a fluorescence-based screen for competitive glutathione-S-transferase (GST) inhibitors. Although an essential, detoxifying enzyme in healthy individuals, GST attacks chemotherapy cytotoxins in cancer patients, limiting the life-saving effects of the treatment. This new fluorescent glutathione molecule and screen for inhibitors provides the search for chemotherapy targeting GST inhibitors with a new and the most efficient technique for screening these inhibitors.

Committee: Dinty Musk Dr. (Advisor) Subjects: Biochemistry; Chemistry; Organic Chemistry

Doctor of Philosophy, The Ohio State University, 2015, Materials Science and Engineering

Aluminum alloy 7075-T6 is susceptible to localized corrosion when used in aerospace applications. Multi-layered coating systems were applied to aluminum alloys to protect corrosion. Deft primer 02GN084, that was approved to be used in US military aircrafts, is of interest because it has showed promising corrosion protection comparing to an effective chromate system. Praseodymium and CaSO4 were found to be in the Deft primer. Praseodymium was added as a primary corrosion inhibitor while CaSO4 served as an extender material. The role of each component was unknown. CaSO4 might play a role synergistically with praseodymium to inhibit corrosion. Leachability of those inhibitors compared to proven chromate system is also important aspect to fully understand inhibitive mechanism in the real world applications. The mechanism of inhibition by CaSO4 was investigated. Sometimes, electrochemical analysis is not sensitive enough for detecting marginal inhibitors. Free corrosion exposure can reveal the marginal effect of corrosion inhibitors. Samples of AA7075-T6 were exposed to chloride solutions with varying pH via static immersion exposure with and without CaSO4 as an inhibitor for times ranging up to 30 days. Pitting corrosion damage was characterized by optical profilometery (OP) to find pit depth and pit area. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to characterize the extent of corrosion. Surface analysis was carried out by X-ray photoelectron spectroscopy (XPS). Results showed that sulfate suppressed pitting corrosion under acidic conditions. Calcium did not appear to contribute to inhibition in any of the evaluations carried out. EIS results showed an increase in polarization resistance in the presence of sulfate. Thermodynamic and XPS data suggest that the protective film formed in the presence of CaSO4 is Al(OH)SO4. The synergistic and cooperative interaction between of Pr and CaSO4 are unknown. Optical profilomet (open full item for complete abstract)

Committee: Rudolph Buchheit (Advisor); Gerald Frankel (Committee Member); Heather Powell (Committee Member) Subjects: Materials Science

Doctor of Philosophy (PhD), Ohio University, 2024, Chemical Engineering (Engineering and Technology)

Oil and gas transmission pipelines are frequently prone to internal corrosion in field environments. Use of organic corrosion inhibitors is an economical and effective way to combat this problem. Their typically amphiphilic inhibitor molecules provide protection by adsorption on the metal surface. Therefore, understanding and quantifying adsorption phenomena has significance for prediction of corrosion inhibition performance of a particular compound. In this dissertation research, a quartz crystal microbalance with dissipation monitoring (QCM-D) was the primary tool used to investigate the adsorption of two corrosion inhibitor model compounds on a noble gold substrate. The research reported herein shows how QCM-D can be used effectively to gain insights about the properties of the adsorbed layer, quantify adsorption/desorption kinetics, make predictions on the possible adsorbed layer configurations, and investigate the influence of inhibitor molecular structure on adsorption phenomena. Since real scenarios involve an actively corroding substrate, a classical oscillatory circuit-based quartz crystal microbalance (QCM) was also used to probe the metal-solution interface for a corroding and corrosion product forming experimental system; this facilitated deciphering the various reaction steps involved. The QCM-D findings in the present research indicate that the geometric surface coverage was less than 100% even for inhibitor concentrations above the surface saturation concentrations. This can help in answering a historical question in corrosion inhibition research about non-zero corrosion rates at inhibitor concentrations corresponding to maximum inhibition. Furthermore, the kinetic adsorption/desorption constants were estimated from the adsorption curves and verified successfully by predicting desorption behavior. This is of great significance, as this methodology can be further extended to study corrosion inhibition and its persistency. Furthermore, this serves as (open full item for complete abstract)

Committee: Srdjan Nešić (Advisor) Subjects: Chemical Engineering

Master of Science, The Ohio State University, 1970, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2024, Animal Sciences

Extraintestinal pathogenic Escherichia coli (ExPEC) presents a substantial public health threat due to its ability to cause severe infections such as urinary tract infections, bloodstream infections, and meningitis. Recent evidence suggests that birds, particularly poultry, may serve as reservoirs for ExPEC strains pathogenic to humans. Avian pathogenic E. coli (APEC), the avian counterpart of ExPEC, causes multisystemic infections known as colibacillosis, resulting in high morbidity, mortality, and economic losses in poultry production. Current APEC control methods, relying on antibiotics and vaccines, face challenges due to rising multidrug resistance and vaccine failures against heterologous serotypes, highlighting the need for novel alternatives. In this study, we synthesized derivatives of a previously characterized piperazine-based quorum sensing inhibitor (QSI), QSI-5, through structural modifications preserving the piperazine core. This resulted in six derivatives, which were screened against APEC O78 using the autoinducer-2 indicator bacteria Vibrio harveyi BB170 to evaluate their efficacy in quorum sensing (QS) inhibition. Two derivatives such as 1-(naphthalen-2-ylmethyl)-4-(3-phenylpropyl)piperazine (OA4-108) and 1-((5-chlorobenzo[b]thiophen-3-yl)methyl)-4-(3-phenylpropyl)piperazine (OA4-109) exhibited enhanced activity at a 50 µM concentration, showing 100% inhibition in the screening assay. These two analogues also inhibited the bacterial motility and biofilm formation and displayed minimal to no toxicity on chicken and sheep red blood cells, chicken and human macrophage cells (HD-11, THP-1), and human intestinal epithelial cells (Caco-2). Additionally, they reduced the survival of APEC O78 in HD-11 and THP-1 cells. In vivo analysis using the wax moth model demonstrated the non-toxicity of these molecules, along with improved larval survival rates and reduced APEC load. Furthermore, OA4-108 and OA4-109 also showed quorum-sensing inhibition in multiple u (open full item for complete abstract)

Committee: Gireesh Rajashekara (Advisor); Timothy J Johnson (Committee Member); James R Fuchs (Committee Member) Subjects: Animal Sciences

Doctor of Philosophy, The Ohio State University, 2024, Biomedical Sciences

Cancer remains one of the most significant challenges in modern medicine, with global incidence steadily rising. In 2022, the American Cancer Society reported 20 million new cancer cases and 9.7 million cancer-related deaths worldwide, a number predicted to reach 35 million by 2050. Initiatives like the Cancer Moonshot program, launched by President Joe Biden in 2016, have spurred collaborations and innovations in cancer research. Understanding cancer biology and developing effective therapeutic interventions are imperative in combating this complex disease. Over decades, significant progress has been made in revealing the molecular mechanisms underlying cancer development, leading to diverse therapeutic options. From traditional approaches like surgery and chemotherapy to novel immunotherapies and targeted therapies, the therapies against cancer have expanded. However, therapy resistance and adverse effects persist, necessitating ongoing research and innovation. Surgery offers a curative option for localized solid tumors, while chemotherapy disrupts cancer cell proliferation. Chemotherapy, often paired with radiation therapy, is standard care for some cancers despite associated adverse effects. Immunotherapy, leveraging the body's immune system, and targeted therapies, selectively targeting molecular anomalies, have transformed cancer care. Yet, tumor heterogeneity and microenvironment composition pose challenges, highlighting the need for continued research. Monoclonal antibodies (mAbs) and immune checkpoint inhibitors have provided targeted treatment options with reduced systemic toxicity. mAbs disrupt key signaling pathways essential for tumor growth and survival, while immune checkpoint inhibitors "release the breaks" of the immune system. Despite success, only a fraction of patients experience clinical benefit, emphasizing the need for predictive biomarkers and understanding the tumor microenvironment's role. The tumor microenvironment (TME) comprises of ca (open full item for complete abstract)

Committee: William Carson III (Advisor) Subjects: Biology; Immunology; Oncology

Doctor of Philosophy, Case Western Reserve University, 2024, Genetics

Pancreatic beta-cell loss and dysfunction is central to the development of diabetes. As the main function, beta-cells produce and secrete insulin to maintain blood glucose homeostasis. Insulin is converted from its precursor proinsulin in a tightly regulated process in the beta-cells, but the regulating mechanism remains largely unknown. Stem-cell derived beta-like cells serve as unlimiting source for cell replacement therapy, however the generated beta-like cells functionally cannot represent the bona fide human islet. Here in this thesis study, functional genomics study was performed to mapping proinsulin regulators and modifying the in vitro pancreatic beta-cell differentiation. We performed a genome-wide CRISPR screen and identified 84 proinsulin regulators, including well-known factors like Pcsk1 and Cpe, that alter intracellular proinsulin/insulin ratio in a mouse -cell line. We found our proinsulin regulators are distinct from the insulin regulators from a previous orthogonal CRISPR screen. Functional annotation of the proinsulin regulators highlights Golgi as the primary organelle for proinsulin storage and regulation: trafficking towards Golgi increases the intra-cellular proinsulin/insulin ratio, while trafficking away from Golgi, including exocytosis and Golgi-to-ER retrograde transport, decreases proinsulin levels. We also mapped mouse quantitative trait loci (QTLs) associated with plasma proinsulin levels and integrated with the CRISPR screen to pinpoint the causal genes within the QTL loci. The protein disulfide isomerase Pdia6 stands out as the strongest hit from both CRISPR screen and the in vivo QTL mapping. Interestingly, knocking down Pdia6 significantly reduced intracellular proinsulin content and exocytotic secretion. Intriguingly, Pdia6-depletion in both human and mouse -cells does not affect the folding status but disturbed proinsulin translation through a UPR-independent mechanism. Our genetic profiles provide mechanistic insights into the (open full item for complete abstract)

Committee: Yan Li (Advisor) Subjects: Biomedical Research; Cellular Biology; Genetics

Doctor of Philosophy, The Ohio State University, 2024, Chemistry

In recent years, proteolysis-targeting chimera (PROTAC) technology has induced a paradigm shift in drug discovery efforts, especially in targeting difficult oncology targets. However, more than 80 percent of the human proteome is beyond the reach of small molecules. Consequently, such targets remain elusive to small-molecule PROTACs as well. Peptides, on the other hand, have superior potential when it comes to targeting proteins traditionally known as ‘undruggable' due to their large surface area, swift and easy identification, ease of modifications, biocompatibility, and low toxicities. However, exploration of peptide based PROTACs is highly limited. One of the major bottlenecks of peptide based PROTACs is the issue of cell permeability. This study presents a pivotal investigation delineating the strategic conversion of a cell-permeable peptide binder into a potent PROTAC entity. This study successfully attempts to develop degraders against pan-Ras for the first time. Ras is a formidable and highly sought-after target in oncology, and our study has validated the enormous potential of peptide PROTACs for targeting such a difficult protein. Similar attempts to convert cell-permeable peptide binders into degraders would significantly expand the chemical space of PROTACs and peptide therapeutics.

Committee: Dehua Pei (Advisor); Dmitri Kudryashov (Committee Member); Dennis Bong (Committee Member) Subjects: Chemistry

Master of Science (MS), Wright State University, 2024, Pharmacology and Toxicology

Many diseases including lupus erythematosus, atopic eczema, and rosacea can be associated with photosensitivity, which is an abnormal response to sunlight. Recent studies by our group have implicated microvesicle particles (MVP) as playing an important role in causing inflammation and systemic immunosuppression. Previous studies show that functional inhibitors of acid sphingomyelinase (FIASMA) can block MVP release in response to ultraviolet B (UVB) radiation or Platelet-activating Factor (PAF) agonist, which are skin stressors. However, more research needs to be conducted to evaluate the role of PAF, UVB and FIASMA in MVP generation and to formulate a therapeutic medication to be potentially used to treat photosensitivity. One of the major obstacles is the limited availability of human skin explants for research use. To investigate the mechanism of MVP generation and inhibition, we have proposed a preclinical model, porcine skin explants, as a substitute for human skin explants, which is comparatively easier to procure. In this study, we used one of five different FIASMA drugs imipramine, amitriptyline, desipramine, nortriptyline, and sertraline in combination with UVB-, PAF-or phorbol ester-mediated MVP release. This study suggests that FIASMA drugs can block MVP release in response to multiple skin stressors on human HaCaT keratinocyte cells, as well as human and porcine skin explants.

Committee: Jeffrey B. Travers M.D., Ph.D. (Advisor); Michael George Kemp Ph.D. (Committee Member); Ravi P. Sahu Ph.D. (Committee Member) Subjects: Immunology; Pharmacology; Toxicology

Doctor of Philosophy, The Ohio State University, 2024, Molecular Genetics

Breast cancer, predominantly characterized by hormone receptor-positive tumors, poses a significant global health concern. Aromatase inhibitors (AIs) such as anastrozole, letrozole, and exemestane have emerged as pivotal therapies for postmenopausal women, offering superior outcomes compared to conventional treatments. However, their effectiveness is hampered by notable side effects, especially Aromatase Inhibitor-Associated Arthralgia (AIAA), which profoundly impacts patient well-being and treatment compliance. Understanding the pharmacokinetics and pharmacodynamics of AIs is essential for optimizing therapeutic strategies and managing adverse effects. We hypothesized that genetic variations in drug-metabolizing enzymes and transporters could contribute to variability in plasma AI concentrations among individuals, potentially influencing the onset of side effects. AIAA, characterized by joint pain and stiffness, remains a subject of intense research, with animal models providing insights into its pathophysiology, albeit requiring further validation. In this study, we developed two simple, precise, and accurate liquid chromatography-mass spectrometry methods for quantifying letrozole and exemestane, representing nonsteroidal and steroidal AIs, respectively. These methods were subsequently applied to measure AIs concentrations in mouse plasma and tissues, allowing for the precise assessment of drug pharmacokinetics across different mouse strains. Various interconnected approaches using in silico, in vitro, and in vivo models revealed intricate interaction of AIs and OATP1B-type transporters. A mouse model was established to further simulate AIAA and investigate the role of transporters in arthralgia development. Lastly, we validated a biomarker that could potentially serve to identify patients with breast cancer who are at risk of AIAA development. This biomarker reflects the activity of a transporter involved in the elimination of AIs and holds promise for indivi (open full item for complete abstract)

Committee: Shuiying Hu (Advisor); Alex Sparreboom (Advisor) Subjects: Pharmacology

Doctor of Philosophy, The Ohio State University, 2024, Biomedical Sciences

Heart failure (HF) is a complex heterogeneous syndrome characterized by altered left ventricular ejection function and impacts over six million individuals in the United States. Among cancer survivors, cardiovascular mortality due to HF is prevalent.1,2 Despite improvements in the medical and surgical management of HF, mortality rates remain high, with only modest improvements in survival during the past decade. Proper systolic heart function requires coordinated activation and force transmission throughout the myocardium. Cardiomyocytes have developed intricate molecular mechanisms to control both electrical and mechanical functions in response to physiological and pathological stressors. Therefore, active targets for diagnostic and therapeutic approaches for HF are currently centered on pathways that influence both the electrical and structural function of cardiomyocytes. The work described herein explores the mechanisms underlying electrical and structural dysfunction in tyrosine kinase inhibitor (TKI) cardiotoxicity and βII-spectrin (Sptbn1) deficient HF. Genetic or acquired (i.e., drug-induced cardiotoxicity) changes in signaling pathways responsible for electrical and structural homeostasis can lead to the development of lethal arrhythmias and HF. Several chemotherapeutic agents, including TKIs, are associated with arrhythmia and HF in patients with or without preexisting cardiovascular disease. It has been postulated that TKIs may induce HF by causing direct myocardial damage, culminating in reduced cardiac inotropy, lusitropy, and chronotropy. However, the mechanisms by which these phenomena develop or contribute to ventricular arrhythmias and cardiac dysfunction are incomplete. We first describe that pazopanib, a second-generation TKI, alters cardiomyocyte excitability in patients using a retrospective chart review and recapitulated these findings in two mouse models using surface electrograms. Cellular and computational model studies revealed th (open full item for complete abstract)

Committee: Sakima Smith (Advisor); Brandon Biesiadecki (Committee Member); Mark Ziolo (Committee Member); Jill Rafael-Fortney (Committee Member); Thomas Hund (Committee Member) Subjects: Cellular Biology; Molecular Biology; Physiology

Doctor of Philosophy, Case Western Reserve University, 2024, Molecular Biology and Microbiology

Antimicrobial resistance is one of the greatest threats to human health. The β-Lactams (including penicillins, cephalosporins, carbapenems, and monobactams) are safe, effective, widely-used antibiotics. Mimicking an essential peptide bond and inhibiting enzymes involved in peptidoglycan biosynthesis, β-lactams disrupt the cell wall, killing susceptible organisms. Bacteria have developed resistance mechanisms to β-lactams, of which β-lactamases are the most prevalent and problematic. β-Lactamases hydrolyze the namesake, four-membered, cyclic amide β-lactam ring essential to the activity of β-lactam antibiotics, rendering them ineffective. Unfortunately, β-lactamases are constantly evolving in clinics and the environment and substrate expansion means fewer antibiotics are available to treat a given infection. Pseudomonas aeruginosa is a commonly multi-drug resistant (MDR) pathogen and Pseudomonas-derived cephalosporinase (PDC) is a chromosomal β-lactamase and major resistance determinant in the species. Herein, we take a comprehensive and multidisciplinary approach to understanding and overcoming PDC-mediated antibiotic resistance. We begin by proposing a standardized numbering scheme for class C β-lactamases, seeking eliminate the confusion that commonly arises when different research groups refer to the same amino acids using different designations. Next, we microbiologically and biochemically characterize and elucidate the mechanism of two PDC variants associated with oxyimino-cephalosporin resistance: a tyrosine to histidine substitution at amino acid 221 (associated with ceftolozane-tazobactam and ceftazidime-avibactam resistance) and the deletion of threonine 289 and proline 290 (associated with cefepime resistance). These variants modify the Ω-loop and R2-loop (regions bounding opposite sides of the active site and playing a crucial role in substrate specificity), respectively. Both variants lead to substrate expansion through a kcat or k3 driven mechanism ass (open full item for complete abstract)

Committee: Robert Bonomo (Advisor); Focco van den Akker (Committee Member); Krisztina Papp-Wallace (Committee Member); W. Henry Boom (Committee Chair) Subjects: Biochemistry; Bioinformatics; Microbiology; Molecular Biology

PhD, University of Cincinnati, 2023, Pharmacy: Pharmaceutical Sciences

Background: Immune checkpoint inhibitors (ICI) have advanced the treatment of patients with non-small cell lung cancer (NSCLC), melanoma, renal cell carcinoma, and other cancers; however, the benefit to patients can vary significantly.1 Real-world data has shown that not all patients respond the same to ICI treatment and even less is known for aging patients that may have co-morbidities, altered gut microbiome, and multiple concomitant medications. Understanding the effect of medications known to alter the microbiome in lung cancer patients who receive ICI treatments has shown to be of importance. The objective of this study is to evaluate overall survival in elderly lung cancer patients receiving a type of ICI, programmed death-1 (PD-1) inhibitors, and medications known to impact the gut microbiome. Methods: Surveillance, Epidemiology, and End Results (SEER)-Medicare is a publicly available database that links the SEER tumor registry data with Medicare enrollment and claims files. A retrospective observational study design was conducted to estimate the overall survival of elderly patients with NSCLC that use antibiotics and ICI medications, focusing on PD-L1 inhibitors, nivolumab and pembrolizumab. The study cohort was determined based on lung cancer histology, claims for nivolumab or pembrolizumab, and continuous enrollment. Claims for outpatient antibiotics or proton pump inhibitors (PPIs) were identified in the Part D file and assigned to 14-day, 30-day, or 60-day comparison groups. Patients with no antibiotic claim within 180 days of initiating ICI therapy were assigned to a control group. We will estimate the effect of concomitant use of PD-1 inhibitors and antibiotics or PPIs on overall survival using Kaplan-Meier and Cox proportional hazards regression models. Results: We identified 3,445 patients that had lung cancer and received PD-1 inhibitors, of whom 1,702 (49%) received an antibiotic and 484 (14%) received a PPI within 60 (open full item for complete abstract)

Committee: Ana Hincapie Ph.D. (Committee Chair); Jianfei (Jeff) Guo Ph.D. (Committee Member); Eric Vick M.D. Ph.D. (Committee Member); Alex Lin Ph.D. (Committee Member); Rowena Schwartz (Committee Member); Roman Jandarov Ph.D. (Committee Member) Subjects: Pharmaceuticals

PhD, University of Cincinnati, 2023, Medicine: Immunology

Anti-human leukocyte antigen antibodies (aHLA Ab) can form during a humoral immune response to non-self HLA encountered during pregnancy, blood transfusion, or transplantation. Due to shared epitopes across HLA alleles, highly sensitized patients can have aHLA Ab that recognize and would destroy an allograft from >99% of deceased donors; thus, their pool of available organs is severely limited compared to non-sensitized patients. To increase organ availability for highly sensitized patients, aHLA Ab must be sustainably reduced which requires depleting their source: plasma cells (PCs). Our group has focused on PC depletion using proteasome inhibitors as PCs are exquisitely dependent on the proteasome to maintain proteostasis due to their high rate of antibody synthesis. Despite significant PC depletion, proteasome inhibitors alone are insufficient to sustainably reduce aHLA Ab. We hypothesized this was in part due to PC residence in protective bone marrow (BM) microenvironments. Because the CXCR4:CXCL12 axis is instrumental in recruiting and maintaining PCs in the BM, we conducted a proof-of-concept clinical trial to determine if CXCR4 antagonism with the small molecule inhibitor, plerixafor, would mobilize PCs out of the BM. We evaluated the effects of plerixafor on PC residence in blood and BM, its safety profile (alone and in combination with the proteasome inhibitor, bortezomib), and the transcriptional impact on BMPCs in HLA-sensitized kidney transplant candidates. We found that plerixafor indeed mobilized PCs to peripheral blood and had varying effects on BM residence depending on the dose of plerixafor and bortezomib used. Single cell RNA-sequencing on BMPCs pre- and post-treatment revealed multiple populations of PCs, with post-treatment enrichment of oxidative phosphorylation, proteasome assembly, cytoplasmic translation, and autophagy-related genes. Follow up in vitro studies using mouse BMPCs demonstrated that dually inhibiting the proteasome and auto (open full item for complete abstract)

Committee: George Deepe M.D. (Committee Chair); David Hildeman Ph.D. (Committee Member); Ervin Woodle M.D. (Committee Member); Krishna Roskin PhD (Committee Member); Kathryn Wikenheiser-Brokamp M.D. (Committee Member); David Plas Ph.D. (Committee Member) Subjects: Immunology

Doctor of Philosophy, University of Akron, 0, Chemical Engineering

Carbon steel rebars embedded in concrete improve the durability and physical performance of concrete structures by increasing its tensile strength. The rebar is initially protected against corrosion due to the formation of a passive film promoted by the concrete's alkaline environment. However, external factors such as Cl‒ attacks can initiate corrosion, resulting in the formation of oxyhydroxides. This causes the volume of the rebar to expand, increasing the pressure that leads to cracking and spalling of the concrete, compromising its structural integrity. To prevent this, corrosion inhibitors are commonly used. These inhibitors include nitrites, nitrates, phosphates, amines, alkanolamines, and carboxylates. Nonetheless, each inhibitor has drawbacks as they can be expensive, toxic, or cause side reactions that can reduce the concrete's durability. Hence, raising the need to design a new novel corrosion inhibitor that is affordable, safe, and effective to be specifically used for reinforced concrete structures near marine environments. The development of new corrosion inhibitors for reinforced concrete is an experimentally based endeavor that is costly and requires extensive amounts of experiments and time. As a result, one way to avoid this demanding process is by using computer aided molecular design (CAMD) with Signature molecular descriptor ‒ a chemical design process never utilized in this research area before. CAMD utilizes the application of computer-implemented algorithms to design and optimize compounds with a specific property of interest. The first step in designing an inhibitor using a CAMD is to create a quantitative structure‒property relationship (QSPR) using Signature descriptors to correlate the occurrence of every Signature to a property of interest. Accordingly, an inverse design will be implemented, and a structure enumeration algorithm will be employed to generate new novel structures with optimized property of interest. This work investi (open full item for complete abstract)

Committee: David M Bastidas (Advisor); Donald P. Visco (Advisor); Zhenmeng Peng (Committee Member); Gregory N. Morscher (Committee Member); Qixin Zhou (Committee Member); Aliaksei Boika (Committee Member) Subjects: Chemical Engineering; Chemistry

Doctor of Philosophy (PhD), Wright State University, 2023, Biomedical Sciences PhD

With its incorporation into clinical practice in the early 1980s, the class of pharmacological agents known as calcineurin inhibitors (CNIs) quickly became the cornerstone of immunosuppressive therapy post-organ transplantation. However, its use is limited by irreversible kidney damage in the form of renal fibrosis. The molecular mechanism by which CNIs induce renal fibrosis remains to be better understood, and to date, there are no specific therapeutic strategies to mitigate this damage. This dilemma presents a critical need to explain mechanisms by which CNIs cause renal damage. Kidneys of patients on chronic CNI therapy show increased expression of the proinflammatory cytokine Transforming Growth Factor β (TGFβ). TGFβ is a multipotent regulator of cell survival, differentiation, proliferation, and extracellular matrix (ECM) production in a variety of tissues. Renal biopsy samples from patients with tacrolimus nephrotoxicity showed both increased mRNA and protein expression of TGFβ along with fibronectin and collagen, additional profibrotic markers. However, the role of TGFβ signaling in CNI-induced renal damage remains to be defined and this gap in knowledge prompts further investigation. To this end, this dissertation will I) determine the role of TGFβ signaling in CNI-induced renal damage (Aim 1) and II) establish whether disruption of TGFβ signaling ameliorates renal damage with CNI-induced immunosuppression (Aim 2). This insight will direct development of newer generation CNI immunosuppressants exhibiting reno-preservative potential. Our group reported that aberrant Transforming Growth Factor-β (TGFβ)/Smad signaling drives the profibrotic effects induced by CNIs. Specifically, we demonstrated that 1) tacrolimus inhibits the calcineurin/NFAT axis while inducing TGFβ ligand secretion and receptor activation in renal fibroblasts, 2) aberrant TGFβ receptor activation stimulates Smad-mediated production of myofibroblast markers, notable features of fibrobla (open full item for complete abstract)

Committee: Clintoria Williams Ph.D. (Advisor); Mark Rich M.D., Ph.D. (Committee Member); Eric Bennett Ph.D. (Committee Member); David Cool Ph.D. (Committee Member); Khalid Elased Pharm.D., Ph.D. (Committee Member) Subjects: Biology; Biomedical Research; Medicine; Pathology; Pharmacology; Physiology