My thesis comprises of two projects, the first which investigates catechol-O-methyltransferase (COMT) protein levels by genotype (chapter 1 and 2), and the second which investigates excitatory amino acid transporter (EAAT)1 and EAAT2 and metabotropic glutamate receptor 5 mRNA levels (chapter 3) in the prefrontal cortex of subjects with schizophrenia.
Project 1. COMT genotype has previously been associated with cognitive function; I hypothesized that COMT genotype would also be associated with differing levels of cortical COMT protein. Using western blotting, I measured protein levels of the two COMT protein isoforms, membrane bound (MB-) COMT and soluble (S-) COMT, as well as beta-actin protein levels, in Brodmann’s area (BA) 9 of 199 individuals, 119 of whom had psychiatric disorders. I have shown that levels of S-COMT protein vary with genotype at rs4818 and rs4680, but not rs737865 and rs165599 (rs4818 genotype: CC
Introduction The majority of children who sustain a concussion will recover quickly, but a significant minority will experience ongoing postconcussive symptoms, known as postconcussion syndrome (PCS). These symptoms include emotional, behavioural, cognitive and physical symptoms and can lead to considerable disability. The neurobiological underpinnings of PCS are poorly understood, limiting potential clinical interventions. As such, patients and families frequently re-present to clinical services, who are often ill equipped to address the multifactorial nature of PCS. This contributes to the high cost of concussion management and the disability of children experiencing PCS. The aims of the present study are: (1) to plot and contrast recovery pathways for children with concussion from time of injury to 3 months postinjury, (ii) evaluate the contribution of acute biomarkers (ie, blood, MRI) to delayed recovery postconcussion and (3) estimate financial costs of child concussion to patients attending the emergency department (ED) of a tertiary children’s hospital and factors predicting high cost. Methods and analysis Take C.A.Re is a prospective, longitudinal study at a tertiary children’s hospital, recruiting and assessing 525 patients aged 5–<18 years (400 concussion, 125 orthopaedic injury) who present to the ED with a concussion and following them at 1–4 days, 2 weeks, 1 month and 3 months postinjury. Multiple domains are assessed: preinjury and postinjury, clinical, MRI, blood samples, neuropsychological, psychological and economic. PCS is defined as the presence of ≥2 symptoms on the Post Concussive Symptoms Inventory rated as worse compared with baseline 1 month postinjury. Main analyses comprise longitudinal Generalised Estimating Equation models and regression analyses of predictors of recovery and factors predicting high economic costs. Ethics and dissemination Ethical approval has been obtained through the Royal Children’s Hospital Melbourne Human Research Ethics Committee (33122). We aim to disseminate the findings through international conferences, international peer-reviewed journals and social media. Trial registration number ACTRN12615000316505; Results.
Abstract In developing brain neuronal migration, dendrite outgrowth and dendritic spine outgrowth are controlled by Cdc42, a small GTPase of the Rho family, and its activators. Cdc42 function in promoting actin polymerization is crucial for glutamatergic synapse regulation. Here, we focus on GABAergic synapse-specific activator of Cdc42, collybistin (CB) and examine functional differences between its splice isoforms CB1 and CB2. We report that CB1 and CB2 differentially regulate GABAergic synapse formation in vitro along proximal-distal axis and adult-born neuron maturation in vivo . The functional specialization between CB1 and CB2 isoforms arises from their differential protein half-life, in turn regulated by ubiquitin conjugation of the unique CB1 C-terminus. We report that CB1 and CB2 negatively regulate Cdc42; however, Cdc42 activation is dependent on CB interaction with gephyrin. During hippocampal adult neurogenesis CB1 regulates neuronal migration, while CB2 is essential for dendrite outgrowth. Finally, using mice lacking Gabra2 subunit, we show that CB1 function is downstream of GABA A Rs, and we can rescue adult neurogenesis deficit observed in Gabra2 KO. Overall, our results uncover previously unexpected role for CB isoforms downstream of α2-containing GABA A Rs during neuron maturation in a Cdc42 dependent mechanism. Author Summary GABAergic inhibition regulates distinct stages of brain development; however, cellular mechanisms downstream of GABA A receptors (GABA A Rs) that influence neuronal migration, maturation and synaptogenesis are less clear. ArfGEF9 encodes for RhoGEF with Cdc42 and TC10 GTPase as its substrates. Interestingly, ArhGEF9 is the only known RhoGEF essential for GABAergic synapse formation and maintenance. We report that during brain development ArfGEF9 mRNA splicing regulation generates different ratios of CB1 and CB2 splice isoforms. CB1 mRNA splicing is enhanced during early brain developmental, while CB2 levels remains constant throughout brain development. We also show that CB1 protein has shorter half-life and ubiquitin proteasome system restricts CB1 abundance within developing neuron to modulate neuron migration and distributing GABAergic synapse along the proximal-distal axis. On the other hand, CB2 isoform although expressed abundantly throughout brain development is essential for neuron dendrite maturation. Together, our data identifies specific post-transcriptional and post-translational mechanisms downstream of GABA A Rs influencing ArhGEF9 function to regulate distinct aspects of neuronal maturation process.
Introduction While most children recover from a concussion shortly after injury, approximately 30% experience persistent postconcussive symptoms (pPCS) beyond 1-month postinjury. Existing research into the treatment of pPCS have evaluated unimodal approaches, despite evidence suggesting that pPCS likely represent an interaction across various symptom clusters. The primary aim of this study is to evaluate the effectiveness of a multimodal, symptom-tailored intervention to accelerate symptom recovery and increase the proportion of children with resolved symptoms at 3 months postconcussion. Methods and analysis In this open-label, assessor-blinded, randomised clinical trial, children with concussion aged 8–18 years will be recruited from The Royal Children’s Hospital (The RCH) emergency department, or referred by a clinician, within 17 days of initial injury. Based on parent ratings of their child’s PCS at ~10 days postinjury, symptomatic children (≥2 symptoms at least 1-point above those endorsed preinjury) will undergo a baseline assessment at 3 weeks postinjury and randomised into either Concussion Essentials (CE, n=108), a multimodal, interdisciplinary delivered, symptom-tailored treatment involving physiotherapy, psychology and education, or usual care (UC, n=108) study arms. CE participants will receive 1 hour of intervention each week, for up to 8 weeks or until pPCS resolve. A postprogramme assessment will be conducted at 3 months postinjury for all participants. Effectiveness of the CE intervention will be determined by the proportion of participants for whom pPCS have resolved at the postprogramme assessment (primary outcome) relative to the UC group. Secondary outcome analyses will examine whether children receiving CE are more likely to demonstrate resolution of pPCS, earlier return to normal activity, higher quality of life and a lower rate of utilisation of health services, compared with the UC group. Ethics and dissemination Ethics were approved by The RCH Human Research Ethics Committee (HREC: 37100). Parent, and for mature minors, participant consent, will be obtained prior to commencement of the trial. Study results will be disseminated at international conferences and international peer-reviewed journals. Trial registration number ACTRN12617000418370; pre-results.
The Sports Concussion Assessment Tool-5th Edition (SCAT5) and the child version (Child SCAT5) are the current editions of the SCAT and have updated the memory testing component from previous editions. This study aimed to validate this new memory component against the Rey Auditory Verbal Learning Test (RAVLT) as the validated standard. This prospective, observational study, carried out within The Royal Children's Hospital Emergency Department, Melbourne, Australia, recruited 198 participants: 91 with concussion and 107 upper limb injury or healthy sibling controls. Partial Pearson correlations showed that memory acquisition and recall on delay aspects of the SCAT5 were significantly correlated with the RAVLT equivalents when controlling for age (p < 0.001, r = 0.565 and p < 0.001, r = 0.341, respectively). Factor analysis showed that all RAVLT and SCAT5 memory components load on to the same factor, accounting for 59.13% of variance. Logistic regression models for both the RAVLT and SCAT5, however, did not predict group membership (p > 0.05). Receiver operating curve analysis found that the area under the curve for all variables and models was below the recommended 0.7 threshold. This study demonstrated that the SCAT5 and Child SCAT5 memory paradigm is a valid measure of memory in concussed children.
Lithium medication is considered to be the first-line treatment for bipolar disorder as a monotherapy, and for treatment-resistant depression with lithium augmentation. However, because of potential toxicity, lithium levels must be monitored frequently. Recent studies have demonstrated a significant correlation between lithium levels measured in serum and those detected in oral fluid, suggesting that oral fluid analysis may represent an easy, noninvasive means to monitor lithium levels. The aim of this study was to evaluate the analytical performance of rapid assays for lithium measurements in oral fluid.
Abstract Measuring Huntingtin (HTT) protein in peripheral cells represents an essential step in biomarker discovery for Huntington’s Disease (HD), however to date, investigations into the salivary expression of HTT has been lacking. In the current study, we quantified total HTT (tHTT) and mutant HTT (mHTT) protein in matched blood and saliva samples using single molecule counting (SMC) immunoassays: 2B7-D7F7 (tHTT) and 2B7-MW1 (mHTT). Matched samples, and clinical data, were collected from 95 subjects: n = 19 manifest HD, n = 34 premanifest HD (PM), and n = 42 normal controls (NC). Total HTT and mHTT levels were not correlated in blood and saliva. Plasma tHTT was significantly associated with age, and participant sex; whereas salivary mHTT was significantly correlated with age, CAG repeat length and CAP score. Plasma and salivary tHTT did not differ across cohorts. Salivary and plasma mHTT were significantly increased in PM compared to NC; salivary mHTT was also significantly increased in HD compared to NC. Only salivary tHTT and mHTT were significantly correlated with clinical measures. Salivary HTT is uniquely associated with clinical measures of HD and offers significant promise as a relevant, non-invasive HD biomarker. Its use could be immediately implemented into both translational and clinical research applications.
Of the four million children who experience a concussion each year, 30-50% of children will experience delayed recovery, where they will continue to experience symptoms more than two weeks after their injury. Delayed recovery from concussion encompasses emotional, behavioral, physical, and cognitive symptoms, and as such, there is an increased focus on developing an objective tool to determine risk of delayed recovery. This study aimed to identify a blood protein signature predictive of delayed recovery from concussion in children. Plasma samples were collected from children who presented to the Emergency Department at the Royal Children's Hospital, Melbourne, within 48h post-concussion. This study involved a discovery and validation phase. For the discovery phase, untargeted proteomics analysis was performed using single window acquisition of all theoretical mass spectra to identify blood proteins differentially abundant in samples from children with and without delayed recovery from concussion. A subset of these proteins was then validated in a separate participant cohort using multiple reaction monitoring and enzyme linked immunosorbent assay. A blood protein signature predictive of delayed recovery from concussion was modeled using a Support Vector Machine, a machine learning approach. In the discovery phase, 22 blood proteins were differentially abundant in age- and sex-matched samples from children with (
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