Saliva microRNA Biomarkers of Cumulative Concussion

Recurrent concussions increase risk for persistent post-concussion symptoms, and may lead to chronic neurocognitive deficits. Little is known about the molecular pathways that contribute to persistent concussion symptoms. We hypothesized that salivary measurement of microribonucleic acids (miRNAs), a class of epitranscriptional molecules implicated in concussion pathophysiology, would provide insights about the molecular cascade resulting from recurrent concussions. This hypothesis was tested in a case-control study involving 13 former professional football athletes with a history of recurrent concussion, and 18 age/sex-matched peers. Molecules of interest were further validated in a cross-sectional study of 310 younger individuals with a history of no concussion (n = 230), a single concussion (n = 56), or recurrent concussions (n = 24). There was no difference in neurocognitive performance between the former professional athletes and their peers, or among younger individuals with varying concussion exposures. However, younger individuals without prior concussion outperformed peers with prior concussion on three balance assessments. Twenty salivary miRNAs differed (adj. p \u3c 0.05) between former professional athletes and their peers. Two of these (miR-28-3p and miR-339-3p) demonstrated relationships (p \u3c 0.05) with the number of prior concussions reported by younger individuals. miR-28-3p and miR-339-5p may play a role in the pathophysiologic mechanism involved in cumulative concussion effects

Diagnosing Mild Traumatic Brain Injury Using Saliva RNA Compared to Cognitive and Balance Testing

BACKGROUND: Early, accurate diagnosis of mild traumatic brain injury (mTBI) can improve clinical outcomes for patients, but mTBI remains difficult to diagnose because of reliance on subjective symptom reports. An objective biomarker could increase diagnostic accuracy and improve clinical outcomes. The aim of this study was to assess the ability of salivary noncoding RNA (ncRNA) to serve as a diagnostic adjunct to current clinical tools. We hypothesized that saliva ncRNA levels would demonstrate comparable accuracy for identifying mTBI as measures of symptom burden, neurocognition, and balance. METHODS: This case‐control study involved 538 individuals. Participants included 251 individuals with mTBI, enrolled ≤14 days postinjury, from 11 clinical sites. Saliva samples (n = 679) were collected at five time points (≤3, 4‐7, 8‐14, 15‐30, and 31‐60 days post‐mTBI). Levels of ncRNAs (microRNAs, small nucleolar RNAs, and piwi‐interacting RNAs) were quantified within each sample using RNA sequencing. The first sample from each mTBI participant was compared to saliva samples from 287 controls. Samples were divided into testing (n = 430; mTBI = 201 and control = 239) and training sets (n = 108; mTBI = 50 and control = 58). The test set was used to identify ncRNA diagnostic candidates and create a diagnostic model. Model accuracy was assessed in the naïve test set. RESULTS: A model utilizing seven ncRNA ratios, along with participant age and chronic headache status, differentiated mTBI and control participants with a cross‐validated area under the curve (AUC) of .857 in the training set (95% CI, .816‐.903) and .823 in the naïve test set. In a subset of participants (n = 321; mTBI = 176 and control = 145) assessed for symptom burden (Post‐Concussion Symptom Scale), as well as neurocognition and balance (ClearEdge System), these clinical measures yielded cross‐validated AUC of .835 (95% CI, .782‐.880) and .853 (95% CI, .803‐.899), respectively. A model employing symptom burden and four neurocognitive measures identified mTBI participants with similar AUC (.888; CI, .845‐.925) as symptom burden and four ncRNAs (.932; 95% CI, .890‐.965). CONCLUSION: Salivary ncRNA levels represent a noninvasive, biologic measure that can aid objective, accurate diagnosis of mTBI

IDENTIFYING OPTIMAL KINETIC PARAMETERS IN QUANTITATIVE PAIRED-AGENT MOLECULAR IMAGING BY APPLYING COMPUTATIONAL BIOLOGY TECHNIQUES

Accurate and sensitive discrimination of cancerous tissue from the healthy tissue has been a difficult problem to deal with, resulting in the incomplete resection of cancerous tissue and giving rise to ‘call-back’ surgery. Fluorescence guided surgery, which employs a fluorescent imaging agent to highlight key molecular differences between cancerous and healthy tissue is a promising approach for improving cancer discrimination during tumor resection surgery. However, conventional fluorescence guided surgery methods have not been optimized in terms of maximizing the contrast of cancer to healthy tissue and nonspecific sources of contrast in images can potentially obfuscate the reliability of such approaches, typically owing to variable vascular permeability and retention kinetics of fluorescent imaging agents in cancerous tissues. Paired-agent approaches have been proposed to account for these nonspecific factors. The approaches employ co-administration of a control (untargeted) imaging agent with a cancer targeted imaging agents, the measured signal of which is used to “normalize” out nonspecific components of targeted agent distribution so that the highest possible contrast between cancer and healthy tissue can be realized. This thesis explores how tumor contrast can be optimized by a ratiometric application of paired-agent imaging approach depending on pharmacokinetic characteristics of the targeted and control imaging-agents used. Overall, two parameters were found to be of upmost importance: 1) the plasma elimination half-life of the imaging agents should be long or large compared to the tissue efflux rate, k2, ideally > 10 h for typical k2 levels; 2) the efflux rate of the imaging agents from the extracellular space to the intravascular space needs to be relatively high in the range of 0.05-0.13 min-1. This thesis also highlights the importance of the appropriate imaging time while quantifying the cell surface receptors. With the use of simulations and animal models this thesis identifies the use of kinetic parameters playing a role in the paired-agent imaging approach. By making use of the paired-agent imaging approach in the fluorescence guided surgery it would be possible to accurately quantify the cancer cell surface receptors to optimize identification of the cancerous tissue from the healthy tissue.M.S. in Biomedical Engineering, May 201