Master of Science (MS), Ohio University, 2024, Chemistry and Biochemistry (Arts and Sciences)

Exploding bridge wire (EBW) detonators containing pentaerythritol tetranitrate (PETN) were aged alongside free flowing PETN powder in ovens ranging from 50 ˚C to 75 ˚C, for up to 18 months in order to evaluate physical properties such as threshold voltage and Fisher specific particle size as well as chemical changes. In order to evaluate the chemical changes, PETN and aged PETN from the detonators were analyzed using ultrahigh pressure liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-QTOF) in order to measure degradation products formed during aging. Following chromatographic analysis, the data was imported into MATLAB utilizing a region of interest (ROI) code that compressed and filtered the data while also maintaining the true mass of ions. Partial least squares (PLS) models were then developed to compare chromatographic data to Fisher specific surface area and threshold voltage of the aged free flowing PETN powder and EBW detonators, respectively. Additionally, feature selection employing a relative standard deviation tile-based variance ranking was used on the chromatographic data to improve PLS models. The PLS models did not present a correlation between the chemistry and the physical properties of the samples even with the feature selection. However, feature selection was able to find significant chemical differences in the data.

Committee: Chris Freye (Advisor); Katherine Cimatu (Advisor) Subjects: Analytical Chemistry; Chemistry

Doctor of Philosophy, University of Toledo, 2023, Chemistry

Elevated levels of endogenous cardiotonic steroids (CTS), such as telocinobufagin (TCB) and marinobufagin (MBG), are observed in patients with chronic kidney disease (CKD). The characteristic six-membered δ-lactone ring structure of CTS is critical for binding to the Na+ /K+-ATPase and subsequent signaling. Paraoxonases (PONs) belong to a family of hydrolytic enzymes that can regulate levels of δ-lactone ring structures, like those found in CTS, rendering them inactive. Clinical studies have reported decreased lactonase activity of PONs in CKD patients and its association with cardiovascular morbidity and mortality. PON's activity is diminished in CKD, yet it is unclear whether it is mechanistically linked to increased CTS levels. This research aimed to enhance the knowledge regarding CTS by exploring their regulation in the body and association with PON enzymes, whose exact physiological substrate(s) is/are still unknown. To bridge these knowledge gaps, this research describes novel methods for extraction, detection, and quantification of CTS using highly specific, sensitive, and accurate analytical techniques, such as ultrahigh-performance liquid chromatography-mass spectrometry (UHPLC-MS) as well as HPLC-photodiode array (PDA). In the first project, a protocol was developed for the extraction, detection and quantification of TCB and MBG. Solid-phase extraction (SPE) with hydrophilic-lipophilic balanced (HLB) cartridges was used for the extraction of CTS from an aqueous solution. The methods were optimized to extract and quantify TCB and MBG from the urine of rats with different genotypes; wild type (WT) and PON3 knockout (KO) subjected to different diets (normal chow and high salt) for 8 weeks. The high salt-treated rats serve as a model for studying CKD, while the wild type rats on normal chow act as controls. The results showed that the urine of SS-PON3 KO rats contained higher CTS levels than urine from SS-WT rats for both control and high-salt samples, sug (open full item for complete abstract)

Committee: Dragan Isailovic (Committee Chair); David Kennedy (Committee Member); Emanuela Gionfriddo (Committee Member); Jianglong Zhu (Committee Member) Subjects: Biomedical Research; Chemistry

Master of Science, The Ohio State University, 2020, Food Science and Technology

Color is a key factor affecting consumer's food choices. Artificial colorants have been used since the late 1800s, however, there is consumer and regulatory push to replace artificial colorants with naturally derived ones due to health and environmental reasons. Anthocyanins (ACN) are widely distributed pigments in plants that may act as antioxidants in the human body but have limited stability in foods. In aged red wines, ACN with a free hydroxyl group at C-5 condensate with a cofactor to form new 4-ring pigments called pyranoanthocyanins (PACN). Like ACN, PACN form naturally in nature and provide health benefits in the human body. They have an orange hue and are more stable than ACN but form slowly and inefficiently. The objective of this study was to produce PACNS faster and more efficiently using caffeic acid (CA) as cofactor and temperature as catalyzer. European elderberries (Sambucus nigra) containing cyanidin-derivatives with free hydroxyl group at C-5 were the ACN source. Elderberry powder was dissolved in water and anthocyanins were semi-purified using a C18 resin and concentrated. The monomeric anthocyanin concentration, measured by the pH differential method, was adjusted close to 25µM with 0.1M phosphoric acid buffer. CA, dissolved in 15% ethanol, was diluted with the buffer to achieve ACN-CA molar ratios of 1:50, 1:100, 1:150, and 1:200 and incubated at 65°C for 8 days. The effect of temperature was tested using a CA saturated ACN solution and incubating the samples at 25°C, 50°C, and 75°C for 4 days. Changes in composition were monitored using uHPLC coupled to PDA and MS/MS detectors. When different temperatures were compared at the same CA concentrations, samples incubated for 24 hr at 25°C had the most pigment remaining (98%). Samples held at 75°C for 72 hr degraded the most (only 30% left). Incubation at 75°C converted about 90% to PACN in 24 hours and about 100% to PACN in 48 hr. When samples of anthocyanin were incubated at the same temper (open full item for complete abstract)

Committee: M. Monica Giusti (Advisor); Jessica Cooperstone (Committee Member); Rafael Jimenez-Flores (Committee Member) Subjects: Food Science

Doctor of Philosophy in Clinical-Bioanalytical Chemistry, Cleveland State University, 2019, College of Sciences and Health Professions

In this dissertation work, a semi-quantitative assay using a lipidomics approach and an absolute quantitative assay using liquid chromatography-mass spectrometry techniques were developed (LC-MS). In the lipidomics approach, ultra-high pressure liquid chromatography in tandem with quadrupole time of flight (UHPLC-QTOF) mass spectrometry was used to profile, compare and quantitate the human plasma lipids in Alzheimer's disease subjects (AD) and normal cognitive controls (NCCs). The purpose of this study is to identify potential plasma lipid markers of AD and to explore the relationships between AD and lipid pathways in humans by using bioinformatic tools. The plasma samples of study subjects were first spiked with a mix of 12 synthetic-lipid internal standards, then total lipids were extracted using a modified Blight-Dyer method and fractionated into phospholipids (PL) and neutral lipids (NL) using the aminopropyl cartridge. The UHPLC-QTOF-MS/MS data were processed and analyzed with corrections of retention time and mass shifts. Molecular features were extracted for lipid identifications based on mass-to-charge ratios, isotopic patterns, adducts, and charge states. Venn diagrams were plotted to group the common and the unique features of lipids between AD patients and NCCs. The common significant molecular features between these two study groups were analyzed using principal component analysis (PCA), partial least squares-discriminant analysis (PLS-DA), and non-parametric Wilcoxon rank-sum t-test with false discovery rate calculated p-values. Quantitative lipidomics was performed on the twenty-eight identified significant common lipids. Our results indicate these significant common lipids between AD patients and NCCs were belong to glycerophospholipids, glycerolipids, and sphingolipids. Gene-lipid centric pathway analysis was performed on these significant lipids to obtain the implicated pathways in AD and to understand it's relation to AD. In absolute (open full item for complete abstract)

Committee: Yan Xu Dr (Committee Chair); Yana Sandlers Dr (Committee Member); Anthony J Berdis Dr (Committee Member); Xue-Long Sun Dr (Committee Member); Yuping Wu Dr (Committee Member) Subjects: Analytical Chemistry; Biochemistry; Bioinformatics

Doctor of Philosophy, The Ohio State University, 2016, Molecular, Cellular and Developmental Biology

Vitamin D, the precursor to the potent steroid hormone calcitriol (1,25(OH)2D), is obtained through synthesis following sunlight exposure, diet and supplements. Vitamin D is first metabolized by CYP2R1 in the liver to produce calcifediol (25(OH)D), a circulating form of vitamin D, which is further converted to 1,25(OH)2D by CYP27B1 primarily in the kidney. 1,25(OH)2D can also be produced by extrarenal CYP27B1 in local tissues, including the breast, functioning in an intracrine, autocrine or paracrine manner. 1,25(OH)2D binds to the vitamin D receptor (VDR) that regulates multiple gene expression. However, most studies reported circulating 25(OH)D level but not the level of 1,25(OH)2D in the target tissue. Laboratory studies indicate that vitamin D should decrease the risk of breast cancer, although epidemiological studies are mixed. Thus, the potential anticancer mechanisms for women remain elusive. In the breast, little is known about the metabolic consequences of vitamin D at the cellular level and how this may potentially impact early breast carcinogenesis. In order to address these issues, blood and tissue samples from 153 healthy women undergoing reduction mammoplasty were used to examine 25(OH)D, 1,25(OH)2D levels and VDR protein expression. These women never had cancer, so findings from their breast tissue would represent biological processes before cancer develops, e.g. early carcinogenesis. I aimed to assess the correlation of blood to breast vitamin D levels, to assess the usefulness of blood levels of 25(OH)D in epidemiology studies as markers for breast levels of 1,25(OH)2D (aim 1), and if there were breast cancer risk factors that affected breast vitamin D levels (aim 2) (Fig. 1.4). I also aimed to determine if there were breast VDR (receptor) that positively correlated to 1,25(OH)2D and 25(OH)D (ligands) (aim 3). To investigate if breast vitamin D alone or with VDR affected breast pre-carcinogenesis, different markers were determined in normal breast (open full item for complete abstract)

Committee: Peter Shields (Advisor); Jeffrey Parvin (Committee Member); Gregory Lesinski (Committee Member); Michael Freitas (Committee Member) Subjects: Biomedical Research; Biostatistics; Endocrinology; Epidemiology; Molecular Biology; Oncology; Womens Studies