Development and Application of Suspect and Nontarget Screening to Characterize Organic Micropollutants in Aquatic Environments of New York State

Organic micropollutants (OMPs) have presented a global challenge to water resources management due to concerns over their adverse impacts on aquatic biota and human health at low exposure concentrations (e.g., at ng/L to μg/L levels in aquatic systems). OMPs encompass an extensive array of synthetic organic compounds (e.g., pharmaceuticals, pesticides, personal care products, household chemicals, industrial additives) and their transformation products. My research has been centered around establishing analytical methods based on liquid chromatography-high-resolution mass spectrometry (LC-HRMS), with a focus on the development and application of suspect and nontarget screening workflows for the identification and prioritization of OMPs in inland lakes, streams, and urban wastewater in New York State. In Chapter 1, I collaborated with volunteers from the Citizens Statewide Lake Assessment Program and scientists at the Upstate Freshwater Institute to conduct the first statewide investigation of OMP occurrence in New York inland lakes. Through this project, I developed a suspect screening method based on LC-HRMS to identify and quantify 65 OMPs in 314 lake water samples collected by volunteers from 111 lakes, ponds, and reservoirs across the state. I also performed partial least squares regression and multiple linear regression analyses to prioritize total dissolved nitrogen, specific conductance, and a wastewater-derived fluorescent organic matter component as the best combination of explanatory predictors for the inter-lake variability in OMP occurrence patterns. I further applied the exposure-activity ratio approach to estimate the potential for biological effects associated with OMPs. My work demonstrated that engaging an established network of citizen volunteers offers a viable approach to increasing the spatiotemporal coverage of OMP monitoring while raising public awareness of their prevalence. In Chapter 2, I collaborated with Drs. Christa Kelleher and Rebecca Schewe to investigate the occurrence patterns of OMPs in streams draining mixed-use watersheds in central New York. I combined the use of polar organic chemical integrative samplers (POCIS) with suspect screening and nontarget screening based on LC-HRMS to identify and quantify 133 OMPs in samples collected from 20 stream sites over two sampling seasons. I also performed hierarchical clustering to establish the co-occurrence profiles of OMPs in connection with watershed attributes indicative of anthropogenic influences. I further evaluated the feasibility of deploying POCIS for estimating daily average loads of OMPs and their potential for biological effects in streams via screening-level risk assessments. My work supported the prospect of combining passive sampling with high-resolution accurate mass screening for the multi-watershed characterization of OMP contamination status in streams. In Chapter 3, I collaborated with colleagues from the School of Public Health to pursue one of the earliest wastewater-based epidemiology studies on population-level substance use during the COVID-19 pandemic. I developed and validated an online solid-phase extraction method for sample preconcentration before LC-HRMS analyses to achieve rapid screening of health and lifestyle-related substances in urban wastewater. I applied this method to quantify the levels of 26 pharmaceuticals and lifestyle chemicals in wastewater influent samples collected from six sewersheds in central New York over a period spanning the rising and falling of COVID-19 prevalence. I back-calculated the population-level consumption rates of antidepressants, antiepileptics, antihistamines, antihypertensives, and central nervous system stimulants and further identified their co-variation with disparities in household income, marital status, and/or age of the contributing populations as well as the detection frequency of SARS-CoV-2 RNA in wastewater and the COVID-19 test positivity within the sewersheds. My work highlighted the utility of high-throughput wastewater analysis for assessing substance use patterns during a public health crisis such as COVID-19

Recent Changes in Drug Abuse Scenario: The Novel Psychoactive Substances (NPS) Phenomenon

copyright 2019 by the authors. Articles in this book are Open Access and distributed under the Creative Commons Attribution (CC BY) license, which allows users to download, copy and build upon published articles, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. The book as a whole is distributed by MDPI under the terms and conditions of the Creative Commons license CC BY-NC-ND.Final Published versio

An alternative approach for assessing drug induced seizures, using non-protected larval zebrafish

As many as 9% of epileptic seizures occur as a result of drug toxicity. Identifying compounds with seizurogenic side effects is imperative for assessing compound safety during drug development, however, multiple marketed drugs still have clinical associations with seizures. Moreover, current approaches for assessing seizurogenicity, namely rodent EEG and behavioural studies, are highly resource intensive. This being the case, alternative approaches have been postulated for assessing compound seizurogenicity, including in vitro, in vivo, and in silico methods. In this thesis, experimental work is presented supporting the use of larval zebrafish as a candidate model organism for developing new seizure liability screening approaches. Larval zebrafish are translucent, meaning they are highly amenable to imaging approaches while offering a more ethical alternative to mammalian research. Zebrafish are furthermore highly fecund facilitating capacity for both high replication and high throughput. The primary goal of this thesis was to identify biomarkers in larval zebrafish, both behavioural and physiological, of compounds that increase seizure liability. The efficacy of this model organism for seizure liability testing was assessed through exposure of larval zebrafish to a mechanistically diverse array of compounds, selected for their varying degrees of seizurogenicity. Their central nervous systems were monitored using a variety of different techniques including light sheet microscopy, local field potential recordings, and behavioural monitoring. Data acquired from these measurements were then analysed using a variety of techniques including frequency domain analysis, clustering, functional connectivity, regression, and graph theory. Much of this analysis was exploratory in nature and is reflective of the infancy of the field. Experimental findings suggest that larval zebrafish are indeed sensitive to a wide range of pharmacological mechanisms of action and that drug actions are reflected by behavioural and direct measurements of brain activity. For example, local field potential recordings revealed electrographic responses akin to pre-ictal, inter-ictal and ictal events identified in humans. Ca2+ imaging using light sheet microscopy found global increases in fluorescent intensity and functional connectivity due to seizurogenic drug administration. In addition, [2] further functional connectivity and graph analysis revealed macroscale network changes correlated with drug seizurogenicity and mechanism of action. Finally, analysis of swimming behaviour revealed a strong correlation between high speed swimming behaviours and administration of convulsant compounds. In conclusion, presented herein are data demonstrating the power of functional brain imaging, LFP recordings, and behavioral monitoring in larval zebrafish for assessing the action of neuroactive drugs in a highly relevant vertebrate model. These data help us to understand the relevance of the 4 dpf larval zebrafish for neuropharmacological studies and reveal that even at this early developmental stage, these animals are highly responsive to a wide range of neuroactive compounds across multiple primary mechanisms of action. This represents compelling evidence of the potential utility of larval zebrafish as a model organism for seizure liability testing

Imaging Physiological and Pathological Activity in the Brain using Electric Impedance Tomography

Electric Impedance Tomography (EIT) is a promising medical imaging technique that reconstructs the internal conductivity of an object from boundary measurements. EIT is currently being used to monitor the lung during ventilation clinically. Amongst other suggested uses for imaging it can also be used to image neuronal function. There are different ways on how EIT can image neuronal function and two of these are tested in this thesis. The overall aim of our work was to advance imaging of physiological and pathological neuronal activity using EIT and assess its potential for future clinical use. In Chapter 1, a general introduction into brain imaging techniques and EIT is given. In Chapter 2, the effect of different anaesthetics on the neuronal signal was assessed to prepare for EIT recordings under anaesthesia. In Chapter 3, we assessed the validity of two biophysical models regarding the behaviour of the impedance in response to alterations in the carrier frequency experimentally. This allowed an assessment of the ideal carrier frequency to image physiological neuronal activity. In Chapter 4, the source of the fast neural signal in EIT is discussed further. In Chapter 5, the possibility of imaging physiological neuronal activity throughout the brain is tested and its limitations are discussed. In Chapter 6, the impedance response to epileptiform activity is characterized and the potential use of EIT in imaging epileptic foci in epilepsy patients is discussed. In Chapter 7, imaging of epileptic foci in subcortical structures is tested using two different ways of imaging with EIT