Melinda Fitzgerald

Partial Transection of Adult Rat Optic Nerve as a Model of Secondary Degeneration in the Central Nervous System

Publisher: Bio-Protocol, LLC

Date: 2018

DOI: 10.21769/BIOPROTOC.3118

Differential responses to increasing numbers of mild traumatic brain injury in a rodent closed‐head injury model

Publisher: Wiley

Date: 27-03-2019

DOI: 10.1111/JNC.14673

Abstract: Following mild traumatic brain injury (mTBI), further mild impacts can exacerbate negative outcomes. To compare chronic damage and deficits following increasing numbers of repeated mTBIs, a closed-head weight-drop model of repeated mTBI was used to deliver 1, 2 or 3 mTBIs to adult female rats at 24 h intervals. Outcomes were assessed at 3 months following the first mTBI. No gross motor, sensory or reflex deficits were identified (p > 0.05), consistent with current literature. Cognitive function assessed using a Morris water maze revealed chronic memory deficits following 1 and 2, but not 3 mTBI compared to shams (p ≤ 0.05). Oxidative damage to DNA was assessed immunohistochemically in the dentate hilus of the hippoc us and splenium of the corpus callosum no changes were observed. IBA1-positive microglia were increased in size in the cortex following 1 mTBI and in the corpus callosum following 2 mTBI compared to shams (p ≤ 0.05) no changes were observed in the dentate hilus. Glial fibrillary acidic protein (GFAP)-positive astrocyte immunoreactivity was assessed in all three brain regions and no chronic changes were observed. Integrity of myelin ultrastructure in the corpus callosum was assessed using transmission electron microscopy. G ratio was decreased following 2 mTBIs compared to shams (p ≤ 0.05) at post hoc level only. The changing patterns of damage and deficits following increasing numbers of mTBI may reflect dynamic responses to small numbers of mTBIs or a conditioning effect such that increasing numbers of mTBIs do not necessarily result in worsening pathology. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at cos.io/our-services/open-science-badges/. Cover Image for this issue: doi: 10.1111/jnc.14508.

An Unexpected Transient Breakdown of the Blood Brain Barrier Triggers Passage of Large Intravenously Administered Nanoparticles

Publisher: Springer Science and Business Media LLC

Date: 04-03-2016

DOI: 10.1038/SREP22595

Abstract: The highly restrictive blood-brain barrier (BBB) plays a critically important role in maintaining brain homeostasis and is pivotal for proper neuronal function. The BBB is currently considered the main limiting factor restricting the passage of large (up to 200 nm) intravenously administered nanoparticles to the brain. Breakdown of the barrier occurs as a consequence of cerebrovascular diseases and traumatic brain injury. In this article, we report that remote injuries in the CNS are also associated with BBB dysfunction. In particular, we show that a focal partial transection of the optic nerve triggers a previously unknown transient opening of the mammalian BBB that occurs in the visual centres. Importantly, we demonstrate that this transient BBB breakdown results in a dramatic change in the biodistribution of intravenously administered large polymeric nanoparticles which were previously deemed as BBB-impermeable.

Multimodal analysis of PEI-mediated Endocytosis of Nanoparticles in Neural Cells

Publisher: American Chemical Society (ACS)

Date: 27-10-2011

DOI: 10.1021/NN2022149

Abstract: Polymer nanoparticles are widely used as a highly generalizable tool to entrap a range of different drugs for controlled or site-specific release. However, despite numerous studies examining the kinetics of controlled release, the biological behavior of such nanoparticles remains poorly understood, particularly with respect to endocytosis and intracellular trafficking. We synthesized polyethylenimine-decorated polymer nanospheres (ca. 100-250 nm) of the type commonly used for drug release and used correlated electron microscopy, fluorescence spectroscopy and microscopy, and relaxometry to track endocytosis in neural cells. These capabilities provide insight into how polyethylenimine mediates the entry of nanoparticles into neural cells and show that polymer nanosphere uptake involves three distinct steps, namely, plasma membrane attachment, fluid-phase as well as clathrin- and caveolin-independent endocytosis, and progressive accumulation in membrane-bound intracellular vesicles. These findings provide detailed insight into how the intracellular delivery of nanoparticles is mediated by polyethylenimine, which is presently the most commonly used nonviral gene transfer agent. This fundamental knowledge may also assist in the preparation of next-generation nonviral vectors.

The effects of a combination of ion channel inhibitors on pathology in a model of demyelinating disease

Publisher: Elsevier BV

Date: 09-2019

DOI: 10.1016/J.MSARD.2019.06.005

Abstract: Multiple sclerosis (MS) has been shown to feature oxidative damage, which can be modelled using the cuprizone model of demyelinating disease. Oxidative damage can occur as a result of excessive influx of calcium ions (Ca This study investigated the effects of limiting excess Ca The effects of three weeks of cuprizone administration and of treatment with a combination of three ion channel inhibitors (Lomerizine, Brilliant Blue G (BBG) and YM872), were semi-quantified immunohistochemically. Outcomes assessed were protein nitration (3-nitrotyrosine (3NT)) oxidative damage to DNA (8-hydroxy deoxyguanosine (8OHDG)), advanced glycation end-products (carboxymethyl lysine (CML)), immunoreactivity of microglia (Iba1) and astrocytes (glial acidic fibrillary protein (GFAP)), densities of oligodendrocyte precursor cells (OPCs) (platelet derived growth factor alpha receptor (PDGFαR) with olig2) and oligodendrocytes (olig2 and CC1), and structural elements of the Node of Ranvier (contactin associated protein (Caspr)). The administration of cuprizone resulted in increased protein nitration, DNA damage, and astrocyte and microglial immunoreactivity, a decrease in the density of oligodendrocytes and OPCs, together with altered structure of the Node of Ranvier and reduced myelin basic protein immunoreactivity. Treatment with the ion channel inhibitor combination significantly lowered protein nitration, increased the density of OPCs and reduced the number of atypical Node of Ranvier complexes other outcomes were unaffected. Our findings suggest that excess Ca

Manipulating cellular interactions of poly(glycidyl methacrylate) nanoparticles using mixed polymer brushes

Publisher: American Chemical Society (ACS)

Date: 22-09-2016

DOI: 10.1021/ACSMACROLETT.6B00613

Abstract: There is a growing need for the development of nanoparticles, with imaging and drug delivery capabilities, to maintain cellular uptake but avoid protein attachment and recognition. In this study we have demonstrated that nanoparticles consisting of a poly(glycidyl methacrylate) (PGMA) core and a mixed brush architecture of methoxypoly(ethylene glycol) and poly(ethylenimine) (mPEG-PEI) on the surface can meet this need. Surface functionalization with PEI alone results in cellular uptake, but rapid protein attachment whereas PEG alone can avoid protein attachment but to the detriment of cellular uptake. A mixed copolymer brush of both PEI and mPEG provides the ideal balance.

Resistance wheel exercise from mid-life has minimal effect on sciatic nerves from old mice in which sarcopenia was prevented

Publisher: Springer Science and Business Media LLC

Date: 08-06-2017

DOI: 10.1007/S10522-017-9714-8

Abstract: The ability of resistance exercise, initiated from mid-life, to prevent age-related changes in old sciatic nerves, was investigated in male and female C57BL/6J mice. Aging is associated with cellular changes in old sciatic nerves and also loss of skeletal muscle mass and function (sarcopenia). Mature adult mice aged 15 months (M) were subjected to increasing voluntary resistance wheel exercise (RWE) over a period of 8 M until 23 M of age. This prevented sarcopenia in the old 23 M aged male and female mice. Nerves of control sedentary (SED) males at 3, 15 and 23 M of age, showed a decrease in the myelinated axon numbers at 15 and 23 M, a decreased g-ratio and a significantly increased proportion of myelinated nerves containing electron-dense aggregates at 23 M. Myelinated axon and nerve diameter, and axonal area, were increased at 15 M compared with 3 and 23 M. Exercise increased myelinated nerve profiles containing aggregates at 23 M. S100 protein, detected with immunoblotting was increased in sciatic nerves of 23 M old SED females, but not males, compared with 15 M, with no effect of exercise. Other neuronal proteins showed no significant alterations with age, gender or exercise. Overall the RWE had no cellular impact on the aging nerves, apart from an increased number of old nerves containing aggregates. Thus the relationship between cellular changes in aging nerves, and their sustained capacity for stimulation of old skeletal muscles to help maintain healthy muscle mass in response to exercise remains unclear.

Oligodendroglia Are Particularly Vulnerable to Oxidative Damage After Neurotrauma In Vivo

Publisher: SAGE Publications

Date: 2018

DOI: 10.1177/1179069518810004

The complex contribution of the astrocyte scar.

Publisher: Medknow

Date: 2016

DOI: 10.4103/1673-5374.187023

Repeated mild traumatic brain injury in female rats increases lipid peroxidation in neurons

Publisher: Springer Science and Business Media LLC

Date: 17-04-2017

DOI: 10.1007/S00221-017-4958-8

Abstract: Negative outcomes of mild traumatic brain injury (mTBI) can be exacerbated by repeated insult. Animal models of repeated closed-head mTBI provide the opportunity to define acute pathological mechanisms as the number of mTBI increases. Furthermore, little is known about the effects of mTBI impact site, and how this may affect brain function. We use a closed head, weight drop model of mTBI that allows head movement following impact, in adult female rats to determine the role of the number and location of mTBI on brain pathology and behaviour. Biomechanical assessment of two anatomically well-defined mTBI impact sites were used, anterior (bregma) and posterior (lambda). Location of the impact had no significant effect on impact forces (450 N), and the weight impact locations were on average 5.4 mm from the desired impact site. No between location vertical linear head kinematic differences were observed immediately following impact, however, in the 300 ms post-impact, significantly higher mean vertical head displacement and velocity were observed in the mTBI lambda trials. Breaches of the blood brain barrier were observed with three mTBI over bregma, associated with immunohistochemical indicators of damage. However, an increased incidence of hairline fractures of the skull and macroscopic haemorrhaging made bregma an unsuitable impact location to model repeated mTBI. Repeated mTBI over lambda did not cause skull fractures and were examined more comprehensively, with outcomes following one, two or three mTBI or sham, delivered at 1 day intervals, assessed on days 1-4. We observe a mild behavioural phenotype, with subtle deficits in cognitive function, associated with no identifiable neuroanatomical or inflammatory changes. However, an increase in lipid peroxidation in a subset of cortical neurons following two mTBI indicates increasing oxidative damage with repeated injury in female rats, supported by increased amyloid precursor protein immunoreactivity with three mTBI. This study of acute events following closed head mTBI identifies lipid peroxidation in neurons at the same time as cognitive deficits. Our study adds to existing literature, providing biomechanics data and demonstrating mild cognitive disturbances associated with diffuse injury, predominantly to grey matter, acutely following repeated mTBI.

Predicting outcome following mild traumatic brain injury: Protocol for the longitudinal, prospective, observational Concussion Recovery (CREST) cohort study

Publisher: BMJ

Date: 05-2021

DOI: 10.1136/BMJOPEN-2020-046460

Abstract: Mild traumatic brain injury (mTBI) is a complex injury with heterogeneous physical, cognitive, emotional and functional outcomes. Many who sustain mTBI recover within 2 weeks of injury however, approximately 10%–20% of in iduals experience mTBI symptoms beyond this ‘typical’ recovery timeframe, known as persistent post-concussion symptoms (PPCS). Despite increasing interest in PPCS, uncertainty remains regarding its prevalence in community-based populations and the extent to which poor recovery may be identified using early predictive markers. (1) Establish a research dataset of people who have experienced mTBI and document their recovery trajectories (2) Evaluate a broad range of novel and established prognostic factors for inclusion in a predictive model for PPCS. The Concussion Recovery Study ( CREST ) is a prospective, longitudinal observational cohort study conducted in Perth, Western Australia. CREST is recruiting adults aged 18–65 from medical and community-based settings with acute diagnosis of mTBI. CREST will create a state-wide research dataset of mTBI cases, with data being collected in two phases. Phase I collates data on demographics, medical background, lifestyle habits, nature of injury and acute mTBI symptomatology. In Phase II , participants undergo neuropsychological evaluation, exercise tolerance and vestibular/ocular motor screening, MRI, quantitative electroencephalography and blood-based biomarker assessment. Follow-up is conducted via telephone interview at 1, 3, 6 and 12 months after injury. Primary outcome measures are presence of PPCS and quality of life, as measured by the Post-Concussion Symptom Scale and the Quality of Life after Brain Injury questionnaires, respectively. Multivariate modelling will examine the prognostic value of promising factors. Human Research Ethics Committees of Royal Perth Hospital (#RGS0000003024), Curtin University (HRE2019-0209), Ramsay Health Care (#2009) and St John of God Health Care (#1628) have approved this study protocol. Findings will be published in peer-reviewed journals and presented at scientific conferences. ACTRN12619001226190.

Oligodendroglia Are Particularly Vulnerable to Oxidative Damage after Neurotrauma In Vivo

Publisher: Society for Neuroscience

Date: 18-06-2018

DOI: 10.1523/JNEUROSCI.1898-17.2018

Comparing modes of delivery of a combination of ion channel inhibitors for limiting secondary degeneration following partial optic nerve transection

Publisher: Springer Science and Business Media LLC

Date: 25-10-2019

DOI: 10.1038/S41598-019-51886-3

Abstract: Injury to the central nervous system is exacerbated by secondary degeneration. Previous research has shown that a combination of orally and locally administered ion channel inhibitors following partial optic nerve injury protects the myelin sheath and preserves function in the ventral optic nerve, vulnerable to secondary degeneration. However, local administration is often not clinically appropriate. This study aimed to compare the efficacy of systemic and local delivery of the ion channel inhibitor combination of lomerizine, brilliant blue G (BBG) and YM872, which inhibits voltage-gated calcium channels, P2X 7 receptors and Ca 2+ permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors respectively. Following a partial optic nerve transection, adult female PVG rats were treated with BBG and YM872 delivered via osmotic mini pump directly to the injury site, or via intraperitoneal injection, both alongside oral administration of lomerizine. Myelin structure was preserved with both delivery modes of the ion channel inhibitor combination. However, there was no effect of treatment on inflammation, either peripherally or at the injury site, or on the density of oligodendroglial cells. Taken together, the data indicate that even at lower concentrations, the combinatorial treatment may be preserving myelin structure, and that systemic and local delivery are comparable at improving outcomes following neurotrauma.

The effects of concentration-dependent morphology of self-assembling RADA16 nanoscaffolds on mixed retinal cultures

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C0NR00666A

Abstract: RADA16 self-assembling peptide nanofiber scaffolds (SAPNSs) have been shown to have positive effects on neural regeneration following injury to the central nervous system in vivo, but mechanisms are unclear. Here we show that RADA16 SAPNSs form scaffolds of increasing fiber density with increasing peptide concentration which in turn has a concentration-dependent effect on neurons and astrocytes in mixed retinal cultures. Importantly, we report that the final nanoscale fiber architecture is an important factor to consider in designing scaffolds to promote regeneration in the central nervous system.

Repeated Long-Term Sub-concussion Impacts Induce Motor Dysfunction in Rats: A Potential Rodent Model

Publisher: Frontiers Media SA

Date: 29-05-2020

DOI: 10.3389/FNEUR.2020.00491

Reduced ryanodine receptor content in isolated neonatal cardiomyocytes compared with the intact tissue

Publisher: Elsevier BV

Date: 10-1994

DOI: 10.1006/JMCC.1994.1145

Abstract: The effects of isolation and culture of rat neonatal ventricular myocytes on the properties of the ryanodine receptor were investigated. [3H]-Ryanodine bound to a single class of sites in membranes prepared from intact neonatal ventricle, with an affinity of 16.3 +/- 2.8 nm (mean +/- S.E. n = 3) and a capacity of 546 +/- 64 fmol/mg protein (mean +/- S.E. n = 3). In contrast, no detectable displaceable binding of [3H]-ryanodine was observed when similar experiments were performed using membranes prepared from isolated neonatal cardiomyocytes. The apparent absence of [3H]-ryanodine binding in the neonatal cardiomyocytes suggested either reduced ryanodine receptor protein or the conversion of the receptors to a low affinity state. To distinguish between these possibilities, the content of ryanodine receptor protein was measured using SDS-PAGE followed by western blotting. Membranes prepared from neonatal ventricle contained substantial amounts of ryanodine receptor, as demonstrated by a dense band on western blots. However the corresponding band in preparations of isolated cells, while having similar electrophoretic mobility, was barely detectable. It is concluded that the ryanodine receptor protein is strongly expressed in intact neonatal ventricle, but the level of expression is markedly reduced upon isolation of the cardiomyocytes. These findings demonstrate that ryanodine receptor expression is significantly down-regulated when rat neonatal ventricular myocytes are isolated and maintained in culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Secondary Degeneration Impairs Myelin Ultrastructural Development in Adulthood following Adolescent Neurotrauma in the Rat Optic Nerve

Publisher: MDPI AG

Date: 07-02-2023

DOI: 10.3390/IJMS24043343

Abstract: Adolescence is a critical period of postnatal development characterized by social, emotional, and cognitive changes. These changes are increasingly understood to depend on white matter development. White matter is highly vulnerable to the effects of injury, including secondary degeneration in regions adjacent to the primary injury site which alters the myelin ultrastructure. However, the impact of such alterations on adolescent white matter maturation is yet to be investigated. To address this, female piebald-virol-glaxo rats underwent partial transection of the optic nerve during early adolescence (postnatal day (PND) 56) with tissue collection two weeks (PND 70) or three months later (PND 140). Axons and myelin in the transmission electron micrographs of tissue adjacent to the injury were classified and measured based on the appearance of the myelin laminae. Injury in adolescence impaired the myelin structure in adulthood, resulting in a lower percentage of axons with compact myelin and a higher percentage of axons with severe myelin decompaction. Myelin thickness did not increase as expected into adulthood after injury and the relationship between the axon diameter and myelin thickness in adulthood was altered. Notably, dysmyelination was not observed 2 weeks postinjury. In conclusion, injury in adolescence altered the developmental trajectory, resulting in impaired myelin maturation when assessed at the ultrastructural level in adulthood.

Inositol 1,4,5-trisphosphate receptor function in neonatal cardiomyocytes

Publisher: Elsevier BV

Date: 07-1994

DOI: 10.1016/0922-4106(94)90200-3

Abstract: We have previously reported that the metabolism of inositol(1,4,5)trisphosphate (Ins(1,4,5)P3) is altered when rat neonatal ventricular cardiomyocytes are isolated and cultured. In the current study we show that the mass content of Ins(1,4,5)P3 is lower in the isolated cells than in the intact tissue. However, the properties of the Ins(1,4,5)P3 receptors were not different in the two preparations and the isolated cells remained insensitive to Ins(1,4,5)P3 in terms of 45Ca2+ release. Thus, despite the altered pattern of metabolism of Ins(1,4,5)P3 in isolated neonatal cells, the properties of the receptors were similar to those reported in other myocardial preparations.

Characterization of polymeric nanoparticles for treatment of partial injury to the central nervous system

Publisher: Elsevier BV

Date: 06-2016

DOI: 10.1016/J.DIB.2016.02.019

Secondary Degeneration of Oligodendrocyte Precursor Cells Occurs as Early as 24 h after Optic Nerve Injury in Rats

Publisher: MDPI AG

Date: 09-02-2023

DOI: 10.3390/IJMS24043463

Abstract: Optic nerve injury causes secondary degeneration, a sequela that spreads damage from the primary injury to adjacent tissue, through mechanisms such as oxidative stress, apoptosis, and blood-brain barrier (BBB) dysfunction. Oligodendrocyte precursor cells (OPCs), a key component of the BBB and oligodendrogenesis, are vulnerable to oxidative deoxyribonucleic acid (DNA) damage by 3 days post-injury. However, it is unclear whether oxidative damage in OPCs occurs earlier at 1 day post-injury, or whether a critical ‘window-of-opportunity’ exists for therapeutic intervention. Here, a partial optic nerve transection rat model of secondary degeneration was used with immunohistochemistry to assess BBB dysfunction, oxidative stress, and proliferation in OPCs vulnerable to secondary degeneration. At 1 day post-injury, BBB breach and oxidative DNA damage were observed, alongside increased density of DNA-damaged proliferating cells. DNA-damaged cells underwent apoptosis (cleaved caspase3+), and apoptosis was associated with BBB breach. OPCs experienced DNA damage and apoptosis and were the major proliferating cell type with DNA damage. However, the majority of caspase3+ cells were not OPCs. These results provide novel insights into acute secondary degeneration mechanisms in the optic nerve, highlighting the need to consider early oxidative damage to OPCs in therapeutic efforts to limit degeneration following optic nerve injury.

Emerging Applications for Quantitative Susceptibility Mapping in the Detection of Traumatic Brain Injury Pathology

Publisher: Elsevier BV

Date: 07-2021

DOI: 10.1016/J.NEUROSCIENCE.2021.05.030

Inflammation and blood-brain barrier breach remote from the primary injury following neurotrauma

Publisher: Springer Science and Business Media LLC

Date: 07-07-2018

DOI: 10.1186/S12974-018-1227-0

Multimodal and multifunctional stealth polymer nanospheres for sustained drug delivery

Publisher: Royal Society of Chemistry (RSC)

Date: 2012

DOI: 10.1039/C2NJ40016B

The impact of exercise, sleep, and diet on neurocognitive recovery from mild traumatic brain injury in older adults: A narrative review

Publisher: Elsevier BV

Date: 07-2021

DOI: 10.1016/J.ARR.2021.101322

A cross-sectional study reporting concussion exposure, assessment and management in Western Australian general practice.

Publisher: Springer Science and Business Media LLC

Date: 02-03-2021

DOI: 10.1186/S12875-021-01384-1

Abstract: General Practitioners (GPs) may be called upon to assess patients who have sustained a concussion despite limited information being available at this assessment. Information relating to how concussion is actually being assessed and managed in General Practice is scarce. This study aimed to identify characteristics of current Western Australian (WA) GP exposure to patients with concussion, factors associated with GPs’ knowledge of concussion, confidence of GPs in diagnosing and managing patients with concussion, typical referral practices and familiarity of GPs with guidelines. In this cross-sectional study, GPs in WA were recruited via the RACGP WA newsletter and shareGP and the consented GPs completed an electronic survey. Associations were performed using Chi-squared tests or Fisher’s Exact test. Sixty-six GPs in WA responded to the survey (response rate = 1.7%). Demographics, usual practice, knowledge, confidence, identification of prolonged recovery as well as guideline and resource awareness of GPs who practised in regional and metropolitan areas were comparable ( p 0.05). Characteristics of GPs were similar between those who identified all symptoms of concussion and distractors correctly and those who did not ( p 0.05). However, 84% of the respondents who had never heard of concussion guidelines were less likely to answer all symptoms and distractors correctly ( p = 0.039). Whilst 78% of the GPs who were confident in their diagnoses had heard of guidelines ( p = 0.029), confidence in managing concussion was not significantly associated with GPs exposure to guidelines. It should be noted that none of the respondents correctly identified signs of concussion and excluded the distractors. Knowledge surrounding concussion guidelines, diagnosis and management varied across GPs in WA. Promotion of available concussion guidelines may assist GPs who lack confidence in making a diagnosis. The lack of association between GPs exposure to guidelines and confidence managing concussion highlights that concussion management may be an area where GPs could benefit from additional education and support.

Reactive species and oxidative stress in optic nerve vulnerable to secondary degeneration

Publisher: Elsevier BV

Date: 11-2014

DOI: 10.1016/J.EXPNEUROL.2014.06.007

Abstract: Secondary degeneration contributes substantially to structural and functional deficits following traumatic injury to the CNS. While it has been proposed that oxidative stress is a feature of secondary degeneration, contributing reactive species and resultant oxidized products have not been clearly identified in vivo. The study is designed to identify contributors to, and consequences of, oxidative stress in a white matter tract vulnerable to secondary degeneration. Partial dorsal transection of the optic nerve (ON) was used to model secondary degeneration in ventral nerve unaffected by the primary injury. Reactive species were assessed using fluorescent labelling and liquid chromatography/tandem mass spectroscopy (LC/MS/MS). Antioxidant enzymes and oxidized products were semi-quantified immunohistochemically. Mitophagy was assessed by electron microscopy. Fluorescent indicators of reactive oxygen and/or nitrogen species increased at 1, 3 and 7days after injury, in ventral ON. LC/MS/MS confirmed increases in reactive species linked to infiltrating microglia/macrophages in dorsal ON. Similarly, immunoreactivity for glutathione peroxidase and haem oxygenase-1 increased in ventral ON at 3 and 7days after injury, respectively. Despite increased antioxidant immunoreactivity, DNA oxidation was evident from 1day, lipid oxidation at 3days, and protein nitration at 7days after injury. Nitrosative and oxidative damage was particularly evident in CC1-positive oligodendrocytes, at times after injury at which structural abnormalities of the Node of Ranvier aranode complex have been reported. The incidence of mitochondrial autophagic profiles was also significantly increased from 3days. Despite modest increases in antioxidant enzymes, increased reactive species are accompanied by oxidative and nitrosative damage to DNA, lipid and protein, associated with increasing abnormal mitochondria, which together may contribute to the deficits of secondary degeneration.

Neurite resposes to ephrin-A5 modulated by BDNF: Evidence for TrkB-EphA interactions

Publisher: Elsevier BV

Date: 10-2008

DOI: 10.1016/J.BBRC.2008.07.110

Abstract: In the developing visual system, growing retinal ganglion cell (RGC) axons are exposed to multiple guidance and growth factors. Furthermore, the relative levels of these factors are differentially regulated as topography is roughly established and then refined. We have shown that during the establishment of rough topography (P3), growth cones of pure and explanted RGCs treated with combinations of BDNF and ephrin-A5-Fc responded differently than RGCs treated with BDNF or ephrin-A5-Fc alone (p=0.0083). The response to the combined treatment mimicked that of RGCs cultured with ephrin-A5-Fc alone once topography refines. The guidance cue receptors EphA and TrkB were shown to co-localise in RGCs in vitro. Furthermore, EphA and TrkB receptors interacted directly in in vitro binding assays. Our results suggest that the conversion of growth cone responses from collapse to stabilisation as topography refines, occurs as a result of interactions between EphA and TrkB receptors.

Elemental Mapping in a Preclinical Animal Model Reveals White Matter Copper Elevation in the Acute Phase of Central Nervous System Trauma

Publisher: American Chemical Society (ACS)

Date: 11-09-2023

DOI: 10.1021/ACSCHEMNEURO.3C00421

Blood-brain barrier disruption and ventricular enlargement are the earliest neuropathological changes in rats with repeated sub-concussive impacts over 2 weeks

Publisher: Research Square Platform LLC

Date: 12-01-2021

DOI: 10.21203/RS.3.RS-141703/V1

Abstract: Repeated sub-concussive impact ( e.g. soccer ball heading), a significantly lighter form of mild traumatic brain injury, is increasingly suggested to cumulatively alter brain structure and compromise neurobehavioural function in the long-term. However, the underlying mechanisms whereby repeated long-term sub-concussion induces cerebral structural and neurobehavioural changes are currently unknown. Here, we utilised an established rat model to investigate the effects of repeated sub-concussion on size of lateral ventricles, cerebrovascular blood-brain barrier (BBB) integrity, neuroinflammation, oxidative stress, and biochemical distribution. Following repeated sub-concussion for 2 weeks, the rats showed significantly enlarged lateral ventricles compared with the rats receiving sham-only procedure. The sub-concussive rats also presented significant BBB dysfunction in the cerebral cortex and hippoc al formation, whilst neuromotor function assessed by beamwalk and rotarod tests were comparable to the sham rats. Immunofluorescent and spectroscopic microscopy analyses revealed no significant changes in neuroinflammation, oxidative stress, lipid distribution or protein aggregation, within the hippoc us and cortex. These data collectively indicate that repeated sub-concussion for 2 weeks induce significant ventriculomegaly and BBB disruption, preceding neuromotor deficits.

Cuprizone feed formulation influences the extent of demyelinating disease pathology

Publisher: Springer Science and Business Media LLC

Date: 19-11-2021

DOI: 10.1038/S41598-021-01963-3

Abstract: Cuprizone is a copper-chelating agent that induces pathology similar to that within some multiple sclerosis (MS) lesions. The reliability and reproducibility of cuprizone for inducing demyelinating disease pathology depends on the animals ingesting consistent doses of cuprizone. Cuprizone-containing pelleted feed is a convenient way of delivering cuprizone, but the efficacy of these pellets at inducing demyelination has been questioned. This study compared the degree of demyelinating disease pathology between mice fed cuprizone delivered in pellets to mice fed a powdered cuprizone formulation at an early 3 week demyelinating timepoint. Within rostral corpus callosum, cuprizone pellets were more effective than cuprizone powder at increasing astrogliosis, microglial activation, DNA damage, and decreasing the density of mature oligodendrocytes. However, cuprizone powder demonstrated greater protein nitration relative to controls. Furthermore, mice fed control powder had significantly fewer mature oligodendrocytes than those fed control pellets. In caudal corpus callosum, cuprizone pellets performed better than cuprizone powder relative to controls at increasing astrogliosis, microglial activation, protein nitration, DNA damage, tissue swelling, and reducing the density of mature oligodendrocytes. Importantly, only cuprizone pellets induced detectable demyelination compared to controls. The two feeds had similar effects on oligodendrocyte precursor cell (OPC) dynamics. Taken together, these data suggest that demyelinating disease pathology is modelled more effectively with cuprizone pellets than powder at 3 weeks. Combined with the added convenience, cuprizone pellets are a suitable choice for inducing early demyelinating disease pathology.

Strategies to limit dysmyelination during secondary degeneration following neurotrauma

Publisher: Medknow

Date: 2014

DOI: 10.4103/1673-5374.135307

Protein corona formation moderates the release kinetics of ion channel antagonists from transferrin-functionalized polymeric nanoparticles

Publisher: Royal Society of Chemistry (RSC)

Date: 2020

DOI: 10.1039/C9RA09523C

Abstract: Transferrin (Tf)-functionalized p(HEMA- ran -GMA) nanoparticles were designed to incorporate and release a water-soluble combination of three ion channel antagonists, identified as a promising therapy for secondary degeneration following neurotrauma.

Mineralocorticoids Restore Quiescent Morphology and Reduce VEGF Receptor Expression in Inflamed Choroidal Endothelial Cells in vitro

Publisher: S. Karger AG

Date: 22-10-2009

DOI: 10.1159/000164799

Abstract: i Background/Aims: /i While the glucocorticoid triamcinolone acetonide (9α-fluoro-16α-hydroxyprednisolone, TA) has been widely administered as a treatment of ocular inflammation, mineralocorticoids have not been tested for their efficacy. i Methods: /i We assessed cellular morphology and actin distribution by immunomicroscopy and light microscopy, membrane permeability with transendothelial resistance and cell surface vascular endothelial growth factor receptor-1 (VEGF-R1) expression by flow cytometry. i Results: /i Fludrocortisone acetate was more effective than TA in restoring quiescent morphology and reducing membrane permeability in phorbol-12-myristate-acetate (PMA)-stimulated choroidal endothelial cells (CECs). Each of the corticosteroids inhibited VEGF-R1 cell surface expression in PMA-responsive CECs. i Conclusion: /i Mineralocorticoids may be of potential use in reducing vascular permeability in ocular disease.

Prolonged glutamate excitotoxicity increases GluR1 immunoreactivity but decreases mRNA of GluR1 and associated regulatory proteins in dissociated rat retinae in vitro

Publisher: Elsevier BV

Date: 05-2015

DOI: 10.1016/J.BIOCHI.2015.03.008

Abstract: Glutamate excitotoxicity contributes to damage following injury to the central nervous system via mechanisms including changes in the expression of receptors, calcium overload, oxidative stress and cell death. Excitotoxicity is triggered by glutamate binding to receptors, including calcium permeable AMPA receptors, which can be upregulated under injury conditions. However, the transcriptional response of AMPA receptor regulatory proteins to excitotoxic conditions is unknown. Here, we use real-time quantitative PCR (RT-qPCR), to determine the effect of prolonged glutamate excitotoxicity on the expression of mRNA encoding for GluR1 and AMPA receptor regulatory proteins in dissociated rat retinal cultures that include neuronal (retinal ganglion cell (RGCs)) and glial (Müller) cell populations. mRNA levels of GluR1 and regulators of the GluR1 subunit of AMPA receptors, including Sap97, Cnih2 and Cnih3, decreased following 6, 24 and 48 h incubation with 5 mM glutamate: related regulators not associated with GluR1 were unaffected. In contrast, GluR1 protein, assessed immunohistochemically, was increased in both RGCs and Müller cells after 24 h glutamate exposure: western blotting analysis was inconclusive. Reductions in mRNA of GluR1 and associated regulators occurred prior to cell death, which was first detected at 24 h, and substantial by 48 h. Exposure to glutamate acutely increased the intracellular calcium concentration in the cultures and by 24 h, reactive oxygen species were increased. Our data suggest a negative feedback mechanism in retinal cells, that down-regulates transcription of genes encoding GluR1 regulatory proteins in response to glutamate exposure. Despite this mechanism, GluR1 protein levels remain increased, and are associated with increased reactive species and cell death. Therapeutic strategies targeting calcium permeable AMPA receptors should take into account that increases in GluR1 protein are not necessarily associated with increases in associated mRNA levels over time.

Myelin sheath decompaction, axon swelling, and functional loss during chronic secondary degeneration in rat optic nerve

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 04-09-2012

DOI: 10.1167/IOVS.12-10080

Abstract: To examine chronic changes occurring at 6 months following partial optic nerve (ON) transection, assessing optic axons, myelin, and visual function. Dorsal ON axons were transected, leaving ventral optic axons vulnerable to secondary degeneration. At 3 and 6 months following partial transection, toluidine-blue stained sections were used to assess dimensions of the ON injury site. Transmission electron microscopy (TEM) images of ventral ON were used to quantify numbers, diameter, area, and myelin thickness of optic axons. Immunohistochemistry and fluoromyelin staining were used to assess semiquantitatively myelin protein, lipids in ventral ON, and retinal ganglion cells (RGCs) in midventral retina. Visuomotor function was assessed using optokinetic nystagmus. Following partial ON transection, optic axons and function remained disrupted at 6 months. Although ventral ON swelling observed at 3 months (P ≤ 0.05) receded to normal by 6 months, ultrastructurally, myelinated axons remained swollen (P ≥ 0.05), and myelin thickness increased (P ≤ 0.05) due to loosening of lamellae and an increase in the number of intraperiodic lines. Axons with decompacted myelin persisted and were distinguished as having large axonal calibers and thicker myelin sheaths. Nevertheless, progressive loss of myelin lipid staining with fluoromyelin was seen at 6 months. Despite no further loss of ventral optic axons between 3 and 6 months (P ≥ 0.05), visuomotor function progressively declined at 6 months following partial transection (P ≤ 0.05). Continued decompaction of myelin, altered myelin structure, and swelling of myelinated axons are persistent features of the chronic phases of secondary degeneration and likely contribute to progressive loss of visual function.

Enabling dual cellular destinations of polymeric nanoparticles for treatment following partial injury to the central nervous system

Publisher: Elsevier BV

Date: 2016

DOI: 10.1016/J.BIOMATERIALS.2015.10.001

Abstract: Following neurotrauma, oxidative stress is spread via the astrocytic syncytium and is associated with increased aquaporin 4 (AQP4), inflammatory cell infiltration, loss of neurons and glia and functional deficits. Herein we evaluate multimodal polymeric nanoparticles functionalized with an antibody to an extracellular epitope of AQP4, for targeted delivery of an anti-oxidant as a therapeutic strategy following partial optic nerve transection. Using fluorescence microscopy, spectrophotometry, correlative nanoscale secondary ion mass spectrometry (NanoSIMS) and transmission electron microscopy, in vitro and in vivo, we demonstrate that functionalized nanoparticles are coated with serum proteins such as albumin and enter both macrophages and astrocytes when administered to the site of a partial optic nerve transection in rat. Antibody functionalized nanoparticles synthesized to deliver the antioxidant resveratrol are effective in reducing oxidative damage to DNA, AQP4 immunoreactivity and preserving visual function. Non-functionalized nanoparticles evade macrophages more effectively and are found more diffusely, including in astrocytes, however they do not preserve the optic nerve from oxidative damage or functional loss following injury. Our study highlights the need to comprehensively investigate nanoparticle location, interactions and effects, both in vitro and in vivo, in order to fully understand functional outcomes.

Metallothionein-IIA promotes neurite growth via the megalin receptor

Publisher: Springer Science and Business Media LLC

Date: 19-07-2007

DOI: 10.1007/S00221-007-1032-Y

Abstract: Metallothionein (MT)-I/II has been shown to be neuroprotective and neuroregenerative in a model of rat cortical brain injury. Here we examine expression patterns of MT-I/II and its putative receptor megalin in rat retina. At neonatal stages, MT-I/II was present in retinal ganglion cells (RGCs) but not glial or amacrine cells megalin was present throughout the retina. Whilst MT-I/II was absent from adult RGC in normal animals and after optic nerve transection, the constitutive megalin expression in RGCs was lost following optic nerve transection. In vitro MT-IIA treatment stimulated neuritic growth: more RGCs grew neurites longer than 25 microm (P < 0.05) in dissociated retinal cultures and neurite extension increased in retinal explants (P < 0.05). MT-IIA treatment of mixed retinal cultures increased megalin expression in RGCs, and pre-treating cells with anti-megalin antibodies prevented MT-IIA-stimulated neurite extension. Our results indicate that MT-IIA stimulates neurite outgrowth in RGCs and may do so via the megalin receptor we propose that neurite extension is triggered via signal transduction pathways activated by the NPxY motifs of megalin's cytoplasmic tail.

Synthesis and toxicology of p-phosphonic acid calixarenes and O-alkylated analogues as potential calixarene-based phospholipids

Publisher: Wiley

Date: 03-2012

DOI: 10.1002/CPLU.201100081

Suppressing regrowth of microfluidic generated drug nanocrystals using polyelectrolyte coatings

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C2RA22790H

Secondary Retinal Ganglion Cell Death and the Neuroprotective Effects of the Calcium Channel Blocker Lomerizine

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 11-2009

DOI: 10.1167/IOVS.09-3717

Abstract: After partial optic nerve (ON) injury, intact retinal ganglion cells (RGCs) undergo secondary death, but the topographic distribution of this death is unknown, and it is unclear which cell death pathways are involved. Although the calcium channel blocker lomerizine reduces RGC death after partial ON injury, it is unknown whether this drug alleviates necrotic or apoptotic death. The dorsal ON was transected in adult Piebald-Virol-Glaxo (PVG) rats, and the site of secondary RGC death was determined using anterograde and retrograde DiI tracing. RGC death was assessed at 2 and 3 weeks. Retrograde tracing with fluorogold injected into the superior colliculus 3 days before euthanatization was used to identify RGCs undergoing secondary death. Overall cell loss was quantified using betaIII-tubulin immunohistochemistry. Lomerizine (30 mg/kg, oral) or vehicle was given twice daily, and retinal wholemounts were analyzed for necrotic morphology (nucleic acid stain) or anticleaved caspase-3 expression at 2 and 3 weeks. Ventral retina was identified as the site of secondary RGC death, and central and dorsal retinae were defined as sites of both primary and secondary death. Overall RGC loss occurred by 2 weeks in central and ventral retina (P < 0.05) and by 3 weeks in dorsal retina (P < 0.05). Secondary RGC death was characterized mainly by necrotic morphology, with caspase-3 expression in some RGCs. Lomerizine reduced secondary necrosis at 2 weeks and secondary caspase-3 expression at 3 weeks. Lomerizine had differential effects on necrotic and apoptotic death with time, but its inability to completely prevent secondary death suggests that full neuroprotection will require combinatorial treatments.

Antioxidant phospholipid calix[4]arene mimics as micellular delivery systems

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C3OB41178H

Abstract: Amphiphilic calix[4]arenes were designed as phospholipid mimics by incorporating PO3H2 or NMe3(+) head groups. Using PC12 cells and three stressors (H2O2, menadione and glutamate), we established safe calix[4]arene levels that are able not only to deliver antioxidant payloads of curcumin, but intriguingly also have inherent antioxidant properties. The calix[4]arenes appear to be potent synthetic antioxidants that could be used as nano-carriers for drug delivery.

Composite fluorescent vesicles based on ionic and cationic amphiphilic calix[4]arenes

Publisher: Royal Society of Chemistry (RSC)

Date: 2012

DOI: 10.1039/C2RA20491F

Connectivity traumatic brain injury Australia – implementing best‐practice research

Publisher: Wiley

Date: 14-09-2023

DOI: 10.1111/ANS.18695

Secondary degeneration of the optic nerve following partial transection : the benefits of lomerizine

Publisher: Elsevier BV

Date: 03-2009

DOI: 10.1016/J.EXPNEUROL.2008.11.026

Abstract: Secondary degeneration is a form of 'bystander' damage that can affect neural tissue both nearby and remote from an initial injury. Partial optic nerve transection is an excellent model in which to unequivocally differentiate events occurring during secondary degeneration from those resulting from primary CNS injury. We analysed the primary injury site within the optic nerve (ON) and intact areas vulnerable to secondary degeneration. Areas affected by the primary injury showed morphological disruption, loss of beta-III tubulin axonal staining, reduced myelinated axon density, greater proteoglycan expression (phosphacan), increased microglia and macrophage numbers and increased oxidative stress. Similar, but less extreme, changes were seen in areas of the optic nerve undergoing secondary degeneration. The CNS-specific L- and T-type calcium channel blocker lomerizine alleviated some of the changes in areas vulnerable to secondary degeneration. Lomerizine reduced morphological disruption, oxidative stress and phosphacan expression, and limited early increases in macrophage numbers. However, lomerizine failed to prevent progressive de-myelination of ON axons. Within the retina, secondary retinal ganglion cell (RGC) death was significant in areas vulnerable to secondary degeneration. Lomerizine protected RGCs from secondary death at 4 weeks but did not fully restore behavioural function (optokinetic nystagmus). We conclude that blockade of calcium channels is neuroprotective and limits secondary degenerative changes following CNS injury. However such an approach may need to be combined with other treatments to ensure long-term maintenance of full visual function.

Does Australia have a concussion âepidemic'?

Publisher: Future Medicine Ltd

Date: 03-2020

DOI: 10.2217/CNC-2019-0015

The Protein Corona of PEGylated PGMA-Based Nanoparticles is Preferentially Enriched with Specific Serum Proteins of Varied Biological Function

Publisher: American Chemical Society (ACS)

Date: 30-10-2017

DOI: 10.1021/ACS.LANGMUIR.7B02568

Abstract: The composition of the protein corona formed on poly(ethylene glycol)-functionalized (PEGylated) poly(glycidyl methacrylate) (PGMA) nanoparticles (NPs) was qualitatively and quantitatively compared to the protein corona on non-PEGylated PGMA NPs. Despite the reputation of PEGylated NPs for stealth functionality, we demonstrate the preferential enrichment of specific serum proteins of varied biological function in the protein corona on PEGylated NPs when compared to non-PEGylated NPs. Additionally, we suggest that the base material of polymeric NPs plays a role in the preferential enrichment of select serum proteins to the hard corona.

Changes to mitochondrial ultrastructure in optic nerve vulnerable to secondary degeneration in vivo are limited by irradiation at 670 nm

Publisher: Springer Science and Business Media LLC

Date: 08-09-2013

DOI: 10.1186/1471-2202-14-98

Abstract: Traumatic injury to the central nervous system results in damage to tissue beyond the primary injury, termed secondary degeneration. Key events thought to be associated with secondary degeneration involve aspects of mitochondrial function which may be modulated by red/near-infrared irradiation therapy (R/NIR-IT), but precisely how mitochondria are affected in vivo has not been investigated. Secondary degeneration was modelled by transecting the dorsal aspect of the optic nerve in adult rats and mitochondrial ultrastructure in intact ventral optic nerve vulnerable to secondary degeneration investigated with transmission electron microscopy. Despite reported increases in fission following central nervous system injury, we saw no change in mitochondrial densities in optic nerve vulnerable to secondary degeneration in vivo . However, in axons, frequency distributions of mitochondrial profile areas showed higher cumulative probabilities of smaller mitochondrial profiles at day 1 after injury. Glial mitochondrial profiles did not exhibit changes in area, but a more elliptical mitochondrial shape was observed at both day 1 and 7 following injury. Importantly, mitochondrial autophagic profiles were observed at days 1 and 7 in optic nerve vulnerable to secondary degeneration in vivo . Citrate synthase activity was used as an additional measure of mitochondrial mass in ventral optic nerve and was decreased at day 7, whereas mitochondrial aconitase activity increased at day 1 and day 28 after injury in optic nerve vulnerable to secondary degeneration. R/NIR-IT has been used to treat the injured central nervous system, with reported improvements in oxidative metabolism suggesting mitochondrial involvement, but ultrastructural information is lacking. Here we show that R/NIR-IT of injured animals resulted in distributions of mitochondrial areas and shape not significantly different from control and significantly reduced mitochondrial autophagic profiles. R/NIR-IT also resulted in decreased citrate synthase activity (day 7) and increased aconitase activity (day 1) in optic nerve vulnerable to secondary degeneration. These findings suggest that mitochondrial structure and activity of enzymes of the citric acid cycle are dynamically altered during secondary degeneration in vivo and R/NIR-IT may protect mitochondrial structure.

Generation of angiostatin by reduction and proteolysis of plasmin: Catalysis by a plasmin reductase secreted by cultured cells

Publisher: Elsevier BV

Date: 08-1997

DOI: 10.1074/JBC.272.33.20641

Retinal genes are differentially expressed in areas of primary versus secondary degeneration following partial optic nerve injury.

Publisher: Public Library of Science (PLoS)

Date: 09-02-2018

DOI: 10.1371/JOURNAL.PONE.0192348

Investigating the link between Later-Life brain volume and cardiorespiratory fitness after mild traumatic brain injury exposure

Publisher: S. Karger AG

Date: 29-09-2023

DOI: 10.1159/000526297

Abstract: b i Introduction: /i /b Evidence suggests that maintaining a higher level of cardiorespiratory fitness (CRF) later in life can offer some protection against brain volume loss as we age. By contrast, mild traumatic brain injury (mTBI) could accelerate age-related cortical atrophy. The current study sought to examine whether variations in the CRF level modified the association between mTBI history and brain volumetric measures in a s le of older adults. b i Methods: /i /b Seventy-nine community-dwelling older adults (mean age 68.7 ± 4.3 years, 54.4% female) were assessed for their mTBI history: 25 participants (32%) reported sustaining at least one lifetime mTBI. Participants also underwent a CRF assessment and magnetic resonance imaging (MRI) to obtain global and region-of-interest volumes. b i Results: /i /b Analysis of covariance, controlling for age, sex, education, and apolipoprotein i (APOE) /i ε4 allele carriage, revealed that participants with a history of mTBI had a significantly larger total mean grey matter volume (582.21 ± 12.46 cm sup /sup ) in comparison to participants with no mTBI history (571.08 ± 17.21 cm sup /sup , i = /i 0.01 after correction for multiple comparisons). However, no differences between groups based on mTBI history were found for total white matter volume or in any other cortical or subcortical structures examined. A subsequent moderation analysis found that CRF was predominantly non-influential on the association between mTBI history and the MRI-quantified measures of brain volume. b i Conclusion: /i /b While unexpected, the findings suggest that a history of mTBI can lead to grey matter alterations in the ageing brain. However, concurrent variations in the CRF level did not influence the differences in brain volume found based on mTBI exposure status.

Early events of Secondary Degeneration after Partial Optic Nerve Transection: An Immunohistochemical Study

Publisher: Mary Ann Liebert Inc

Date: 02-2010

DOI: 10.1089/NEU.2009.1112

Abstract: Secondary degeneration in the central nervous system involves indirect damage to neurons and glia away from the initial injury. Partial transection of the dorsal optic nerve (ON) results in precise spatial separation of the primary trauma from delayed degenerative events in ventrally placed axons and parent somata. Here we conduct an immunohistochemical survey of secondary cellular changes in and around axons and their parent retinal ganglion cell (RGC) somata during the first 3 days after a restricted, dorsal ON transection. This is before the secondary loss of RGCs and axons projecting through the uninjured, ventral portion of the ON. Within 5 min, manganese superoxide dismutase (MnSOD a marker of oxidative stress) co-localizes within the astrocytic network across the entire profile of the ON. Secondary astrocyte hypertrophy of immunofluorescent labeling was evident from 3 h, with sustained increases in myelin basic protein immunoreactivity across the nerve by 24 h. Increases in NG-2-positive oligodendrocyte precursor cells, ED-1-positive activated microglia/macrophages, and Iba1-positive reactive resident microglia/macrophage numbers were only seen in ON vulnerable to secondary degeneration by 3 days. Changes within RGC somata exclusively vulnerable to secondary degeneration were detected at 24 h, as evidenced by increases in MnSOD immunoreactivity, followed by increases in c-jun immunoreactivity at 3 days. Treatment with the voltage-gated calcium channel blocker lomerizine did not alter any measured outcome. We conclude that oxidative stress spreading via the astrocytic network and from injured axons to parent RGC somata is an early event during secondary degeneration, and containment is likely to be required in order to prevent further damage to the nerve.

The influence of NaYF₄:Yb,Er size/phase on the multimodality of co-encapsulated magnetic photon-upconverting polymeric nanoparticles

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C4DT01597E

Abstract: Assessment of polymeric nanoparticles incorporating NaYF 4 :Yb,Er and Fe 3 O 4 as multimodal imaging probes in vitro .

Damage Mechanisms to Oligodendrocytes and White Matter in Central Nervous System Injury: The Australian Context

Publisher: Mary Ann Liebert Inc

Date: 03-2020

DOI: 10.1089/NEU.2019.6890

Elevation of oxidative stress indicators in a pilot study of plasma following traumatic brain injury

Publisher: Elsevier BV

Date: 2017

DOI: 10.1016/J.JOCN.2016.09.006

Abstract: Traumatic brain injury (TBI) encompasses a broad range of injury mechanisms and severity. A detailed determination of TBI severity can be a complex challenge, with current clinical tools sometimes insufficient to tailor a clinical response to a spectrum of patient needs. Blood biomarkers of TBI may supplement clinical assessments but currently available biomarkers have limited sensitivity and specificity. While oxidative stress is known to feature in damage mechanisms following TBI, investigation of blood biomarkers of oxidative stress has been limited. This exploratory pilot study of a subset of 18 trauma patients with TBI of varying severity, quantifies circulating concentrations of the structural damage indicators S100b, and myelin basic protein (MBP), and the biomarkers of oxidative stress hydroxynonenal (HNE), malondialdehyde (MDA), carboxy-methyl-lysine (CML), and 8-hydroxy-2'-deoxy-guanosine (8-OHDG). Significant increases in circulating S100b, MBP, and HNE were observed in TBI patient s les compared to 8 uninjured controls, and there was a significant decrease in CML. This small exploratory study supports the current literature on S100b and MBP elevation in TBI, and reveals potential for the use of peripheral oxidative stress markers to assist in determination of TBI severity. Further investigation is required to validate results and confirm trends.

Neuroprotective peptides fused to arginine-rich cell penetrating peptides: Neuroprotective mechanism likely mediated by peptide endocytic properties.

Publisher: Elsevier BV

Date: 09-2015

DOI: 10.1016/J.PHARMTHERA.2015.06.002

Abstract: Several recent studies have demonstrated that TAT and other arginine-rich cell penetrating peptides (CPPs) have intrinsic neuroprotective properties in their own right. Ex les, we have demonstrated that in addition to TAT, poly-arginine peptides (R8 to R18 containing 8-18 arginine residues) as well as some other arginine-rich peptides are neuroprotective in vitro (in neurons exposed to glutamic acid excitotoxicity and oxygen glucose deprivation) and in the case of R9 in vivo (after permanent middle cerebral artery occlusion in the rat). Based on several lines of evidence, we propose that this neuroprotection is related to the peptide's endocytosis-inducing properties, with peptide charge and arginine residues being critical factors. Specifically, we propose that during peptide endocytosis neuronal cell surface structures such as ion channels and transporters are internalised, thereby reducing calcium influx associated with excitotoxicity and other receptor-mediated neurodamaging signalling pathways. We also hypothesise that a peptide cargo can act synergistically with TAT and other arginine-rich CPPs due to potentiation of the CPPs endocytic traits rather than by the cargo-peptide acting directly on its supposedly intended intracellular target. In this review, we systematically consider a number of studies that have used CPPs to deliver neuroprotective peptides to the central nervous system (CNS) following stroke and other neurological disorders. Consequently, we critically review evidence that supports our hypothesis that neuroprotection is mediated by carrier peptide endocytosis. In conclusion, we believe that there are strong grounds to regard arginine-rich peptides as a new class of neuroprotective molecules for the treatment of a range of neurological disorders.

A Review of ex vivo Elemental Mapping Methods to Directly Image Changes in the Homeostasis of Diffusible Ions (Na+, K+, Mg2 +, Ca2 +, Cl–) Within Brain Tissue

Publisher: Frontiers Media SA

Date: 22-01-2020

DOI: 10.3389/FNINS.2019.01415

INOSITOL‐1,4,5‐TRISPHOSPHATE [INS(1,4,5)P3] AND INS(1,4,5)P3 RECEPTOR CONCENTRATIONS IN HEART TISSUES

Publisher: Wiley

Date: 03-1994

DOI: 10.1111/J.1440-1681.1994.TB02509.X

Abstract: 1. The isolation and culture of neonatal cardiomyocytes causes changes in the metabolism of inositol(1,4,5) trisphosphate (Ins(1,4,5)P3) from primarily dephosphorylation in the intact tissue to a combination of phosphorylation and dephosphorylation in the cultured cells (Woodcock et al. 1992). 2. The content of Ins(1,4,5)P3 was found to be higher in intact heart tissue than in the isolated neonatal cells (10.9 +/- 1.3 and 0.5 +/- 0.1 pmol/mg tissue, mean +/- s.e.m., n = 4, P < 0.002, respectively). 3. Despite this difference, Ins(1,4,5)P3 receptors in intact tissue and in isolated cells were not different in terms of affinity (8.0 +/- 1.7 and 10.9 +/- 1.6 nmol/L, n = 3, respectively) or concentration (143.3 +/- 20.5 and 91.2 +/- 16.0 fmol/mg protein, n = 3, respectively). 4. Thus, while there appears to be a relationship between the tissue content of Ins(1,4,5)P3 and its metabolism, no relationship to the properties of Ins(1,4,5)P3 receptors could be demonstrated.

Simultaneous flow cytometric characterization of multiple cell types and metabolic states in the rat brain after repeated mild traumatic brain injury

Publisher: Elsevier BV

Date: 07-2021

DOI: 10.1016/J.JNEUMETH.2021.109223

Neuromodulation for Mild Traumatic Brain Injury Rehabilitation

Publisher: Frontiers Media SA

Date: 11-12-2020

DOI: 10.3389/FNHUM.2020.598208

Abstract: Background: Mild traumatic brain injury (mTBI) results from an external force to the head or body causing neurophysiological changes within the brain. The number and severity of symptoms can vary, with some in iduals experiencing rapid recovery, and others having persistent symptoms for months to years, impacting their quality of life. Current rehabilitation is limited in its ability to treat persistent symptoms and novel approaches are being sought to improve outcomes following mTBI. Neuromodulation is one technique used to encourage adaptive neuroplasticity within the brain. Objective: To systematically review the literature on the efficacy of neuromodulation in the mTBI population. Method: A systematic review was conducted using Medline, Embase, PsycINFO, PsycARTICLES and EBM Review. Preferred Reporting Items for Systematic Reviews and the Synthesis Without Meta-analysis reporting guidelines were used and a narrative review of the selected studies was completed. Fourteen articles fulfilled the inclusion criteria which were published in English, investigating an adult s le and using a pre- and post-intervention design. Studies were excluded if they included non-mild TBI severities, pediatric or older adult populations. Results: Thirteen of fourteen studies reported positive reductions in mTBI symptomatology following neuromodulation. Specifically, improvements were reported in post-concussion symptom ratings, headaches, dizziness, depression, anxiety, sleep disturbance, general disability, cognition, return to work and quality of life. Normalization of working memory activation patterns, vestibular field potentials, hemodynamics of the dorsolateral prefrontal cortex and excessive delta wave activity were also seen. The studies reviewed had several methodological limitations including small, heterogenous s les and varied intervention protocols, limiting generalisability. Further research is required to understand the context in which neuromodulation may be beneficial. Conclusions: While these positive effects are observed, limitations included unequal representation of neuromodulation modalities in the literature, and lack of literature describing the efficacy of neuromodulation on the development or duration of persistent mTBI symptoms. Better clarity regarding neuromodulation efficacy could have a significant impact on mTBI patients, researchers, clinicians, and policy makers, facilitating a more productive post-mTBI population. Despite the limitations, the literature indicates that neuromodulation warrants further investigation. PROSPERO registration number: CRD42020161279.

The Effects of a Combination of Ion Channel Inhibitors in Female Rats Following Repeated Mild Traumatic Brain Injury

Publisher: MDPI AG

Date: 31-10-2018

DOI: 10.3390/IJMS19113408

Abstract: Following mild traumatic brain injury (mTBI), the ionic homeostasis of the central nervous system (CNS) becomes imbalanced. Excess Ca2+ influx into cells triggers molecular cascades, which result in detrimental effects. The authors assessed the effects of a combination of ion channel inhibitors (ICI) following repeated mTBI (rmTBI). Adult female rats were subjected to two rmTBI weight-drop injuries 24 h apart, sham procedures (sham), or no procedures (normal). Lomerizine, which inhibits voltage-gated calcium channels, was administered orally twice daily, whereas YM872 and Brilliant Blue G, inhibiting α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and P2X7 receptors, respectively, were delivered intraperitoneally every 48 h post-injury. Vehicle treatment controls were included for rmTBI, sham, and normal groups. At 11 days following rmTBI, there was a significant increase in the time taken to cross the 3 cm beam, as a sub-analysis of neurological severity score (NSS) assessments, compared with the normal control (p 0.05), and a significant decrease in learning-associated improvement in rmTBI in Morris water maze (MWM) trials relative to the sham (p 0.05). ICI-treated rmTBI animals were not different to sham, normal controls, or rmTBI treated with vehicle in all neurological severity score and Morris water maze assessments (p 0.05). rmTBI resulted in increases in microglial cell density, antioxidant responses (manganese-dependent superoxide dismutase (MnSOD) immunoreactivity), and alterations to node of Ranvier structure. ICI treatment decreased microglial density, MnSOD immunoreactivity, and abnormalities of the node of Ranvier compared with vehicle controls (p 0.01). The authors’ findings demonstrate the beneficial effects of the combinatorial ICI treatment on day 11 post-rmTBI, suggesting an attractive therapeutic strategy against the damage induced by excess Ca2+ following rmTBI.

Towards the Development of an Integrative, Evidence-Based Suite of Indicators for the Prediction of Outcome Following Mild Traumatic Brain Injury

Publisher: MDPI AG

Date: 02-01-2020

DOI: 10.3390/BRAINSCI10010023

Abstract: Background: Persisting post-concussion symptoms (PPCS) is a complex, multifaceted condition in which in iduals continue to experience the symptoms of mild traumatic brain injury (mTBI concussion) beyond the timeframe that it typically takes to recover. Currently, there is no way of knowing which in iduals may develop this condition. Method: Patients presenting to a hospital emergency department (ED) within 48 h of sustaining a mTBI underwent neuropsychological assessment and demographic, injury-related information and blood s les were collected. Concentrations of blood-based biomarkers neuron specific enolase, neurofilament protein-light, and glial fibrillary acidic protein were assessed, and a subset of patients also underwent diffusion tensor–magnetic resonance imaging both relative to healthy controls. In iduals were classified as having PPCS if they reported a score of 25 or higher on the Rivermead Postconcussion Symptoms Questionnaire at ~28 days post-injury. Univariate exact logistic regression was performed to identify measures that may be predictive of PPCS. Neuroimaging data were examined for differences in fractional anisotropy (FA) and mean diffusivity in regions of interest. Results: Of n = 36 in iduals, three (8.33%) were classified as having PPCS. Increased performance on the Repeatable Battery for the Assessment of Neuropsychological Status Update Total Score (OR = 0.81, 95% CI: 0.61–0.95, p = 0.004), Immediate Memory (OR = 0.79, 95% CI: 0.56–0.94, p = 0.001), and Attention (OR = 0.86, 95% CI: 0.71–0.97, p = 0.007) indices, as well as faster completion of the Trails Making Test B (OR = 1.06, 95% CI: 1.00–1.12, p = 0.032) at ED presentation were associated with a statistically significant decreased odds of an in idual being classified as having PPCS. There was no significant association between blood-based biomarkers and PPCS in this small s le, although glial fibrillary acidic protein (GFAP) was significantly increased in in iduals with mTBI relative to healthy controls. Furthermore, relative to healthy age and sex-matched controls (n = 8), in iduals with mTBI (n = 14) had higher levels of FA within the left inferior frontal occipital fasciculus (t (18.06) = −3.01, p = 0.008). Conclusion: Performance on neuropsychological measures may be useful for predicting PPCS, but further investigation is required to elucidate the utility of this and other potential predictors.

Specific ion channels contribute to key elements of pathology during secondary degeneration following neurotrauma

Publisher: Springer Science and Business Media LLC

Date: 14-08-2017

DOI: 10.1186/S12868-017-0380-1

Multifunctional nanoadditives for the thermodynamic and kinetic stabilization of enzymes

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C1NR10786K

Abstract: Stabilization of enzymes has become a major focus in the quest to improve the activity, sustainability and recyclability of enzymes for their successful integration into both industry and medicine. Here, we describe the kinetic and thermodynamic stabilization of a variety of enzymes in the presence of cationic multifunctional polymeric nanoparticles.

Iron Oxide-Induced Thermal Effects on Solid-State Upconversion Emissions in NaYF₄:Yb,Er Nanocrystals

Publisher: American Chemical Society (ACS)

Date: 13-08-2013

DOI: 10.1021/AM401837H

Abstract: Multifunctional materials exhibiting photon upconversion show promising applications for biological imaging and sensing. In this study, we examine the solid-state upconversion emission of NaYF4:Yb,Er nanoparticles in the presence of iron oxide nanoparticles. Fe3O4 nanoparticles (6 nm) were mixed with NaYF4:Yb,Er nanoparticles (either 10 or 50 nm) in varying proportions by drying chloroform solutions of nanoparticles onto glass slides. Upconversion spectra were acquired, and a laser power-dependent emission was observed and correlated with the iron oxide content in the mixture. Changes in the lattice temperature of the upconverting particles were monitored by careful observation of the relative intensities of the (2)H11/2 and (4)S3/2 →( 4)I15/2 transitions. The emission characteristics observed are consistent with an iron oxide-induced thermal effect that is dependent on both the laser power and the proportion of iron oxide. The results highlight that the thermal effects of mixed nanoparticle systems should be considered in the design of luminescent upconverting hybrid materials.

An improved assay for the spectrophotometric determination of chondroitinase ABC activity

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C3NJ00168G

Changes in subtypes of Ca microdomains following partial injury to the central nervous system

Publisher: Oxford University Press (OUP)

Date: 2014

DOI: 10.1039/C3MT00336A

Abstract: Nanoscale secondary ion mass spectrometry demonstrates that subsets of Ca microdomains rapidly decrease after central nervous system injury.

Limited restoration of visual function after partial optic nerve injury; a time course study using the calcium channel blocker lomerizine

Publisher: Elsevier BV

Date: 03-2010

DOI: 10.1016/J.BRAINRESBULL.2009.11.004

Abstract: Secondary degeneration is a process encompassing damage adjacent to a primary injury, usually involving increased Ca(2+) influx into neurons and glia. Lomerizine dihydrochloride is a calcium channel blocker with relatively selective CNS effects, currently in clinical trials for glaucoma. We have recently demonstrated that, following partial transection of the optic nerve (ON), 1 month of lomerizine treatment protects retinal ganglion cells (RGCs), incompletely preserves visual function and also limits elements of secondary degeneration, including macrophage infiltration. However, under some circumstances macrophages have been shown to have different supportive effects on RGC protection and regeneration, casting doubt on the benefit of longer term therapies that reduce macrophage numbers. Here, we determined whether shorter treatment times (1 day or 1 week) result in improved effects on RGC survival and visual function, and whether benefits are maintained after cessation of treatment. We demonstrate that 1 month of lomerizine is the minimum period required to restore the fast reset phase of the optokinetic nystagmus and maintain it for a further 2 months after cessation of treatment (p>0.05, not different from normal). While 1 week of lomerizine treatment results in temporary recovery of numbers of fast reset phases, the recovery is not maintained after treatment cessation. Similarly, protection of RGC densities requires 1 month of lomerizine treatment, but protection is not maintained after treatment cessation. Importantly, none of the lomerizine treatment protocols resulted in full restoration of visual function, confirming the necessity of combining lomerizine with other treatment modalities.

Early In Vivo Changes in Calcium Ions, Oxidative Stress Markers, and Ion Channel Immunoreactivity Following Partial Injury to the Optic Nerve

Publisher: Wiley

Date: 31-10-2012

DOI: 10.1002/JNR.22784

Abstract: CNS injury is often localized but can be followed by more widespread secondary degenerative events that usually result in greater functional loss. Using a partial transection model in rat optic nerve (ON). we recently demonstrated in vivo increases in the oxidative stress-associated enzyme MnSOD 5 min after injury. However, mechanisms by which early oxidative stress spreads remain unclear. In the present study, we assessed ion distributions, additional oxidative stress indicators, and ion channel immunoreactivity in ON in the first 24 hr after partial transection. Using nanoscale secondary ion mass spectroscopy (NanoSIMS), we demonstrate changes in the distribution pattern of Ca ions following partial ON transection. Regions of elevated Ca ions in normal ON in vivo rapidly decrease following partial ON transection, but there is an increasingly punctate distribution at 5 min and 24 hr after injury. We also show rapid decreases in catalase activity and later increases in immunoreactivity of the advanced glycation end product carboxymethyl lysine in astrocytes. Increased oxidative stress in astrocytes is accompanied by significantly increased immunoreactivity of the AMPA receptor subunit GluR1 and aquaporin 4 (AQP4). Taken together, the results indicate that Ca ion changes and oxidative stress are early events following partial ON injury that are associated with changes in GluR1 AMPA receptor subunits and altered ionic balance resulting from increased AQP4.

Poly(glycidyl methacrylate) coated dual mode upconverting nanoparticles for neuronal cell imaging

Publisher: Royal Society of Chemistry (RSC)

Date: 2016

DOI: 10.1039/C5NJ03368C

Abstract: NaGdF 4 :Yb,Er nanoparticles with a functional poly(glycidyl methacrylate) (PGMA) coating, as a biocompatible multimodal formulation for neuronal cell imaging.

Elucidating the Inability of Functionalized Nanoparticles to Cross the Blood–Brain Barrier and Target Specific Cells in Vivo

Publisher: American Chemical Society (ACS)

Date: 31-05-2019

DOI: 10.1021/ACSAMI.9B01356

Abstract: The adsorption of serum proteins on the surface of nanoparticles (NPs) delivered into a biological environment has been known to alter NP surface properties and consequently their targeting efficiency. In this paper, we use random copolymer (p(HEMA- ran-GMA))-based NPs synthesized using 2-hydroxyethyl methacrylate (HEMA) and glycidyl methacrylate (GMA). We show that serum proteins bind to the NP and that functionalization with antibodies and peptides designed to facilitate NP passage across the blood-brain barrier (BBB) to bind specific cell types is ineffective. In particular, we use systematic in vitro and in vivo analyses to demonstrate that p(HEMA- ran-GMA) NPs functionalized with HIV-1 trans-activating transcriptor peptide (known to cross the BBB) and α neural/glial antigen 2 (NG2) (known for targeting oligodendrocyte precursor cells (OPCs)), in idually and in combination, do not specifically target OPCs and are unable to cross the BBB, likely due to the serum protein binding to the NPs.

Localized, time-dependent responses of rat cranial bone to repeated mild traumatic brain injuries

Publisher: Cold Spring Harbor Laboratory

Date: 13-12-2021

DOI: 10.1101/2021.12.12.472300

Abstract: While it is well-established that bone responds dynamically to mechanical loading, the effects of mild traumatic brain injury (mTBI) on cranial bone composition are unclear. We hypothesized that repeated mTBI (rmTBI) would change the microstructure of cranial bones, without gross skull fractures. To address this, young adult female Piebald Viral Glaxo rats received sham, 1x, 2x or 3x closed-head mTBIs delivered at 24h intervals, using a weight-drop device custom built for reproducible impact. Skull bones were collected at 2 or 10 weeks after the final injury/sham procedure, imaged by micro computed tomography and analyzed at predetermined regions of interest. In the interparietal bone, proximal to the injury site, modest increases in bone thickness was observed at 2 weeks, particularly following 3x mTBI. By 10 weeks, 2x mTBI induced a robust increase in the volume and thickness of the interparietal bone, alongside a corresponding decrease in the volume of marrow cavities in the diploë region. In contrast, neither parietal nor frontal skull s les were affected by rmTBI. Our findings demonstrate time- and location-dependent effects of rmTBI on cranial bone structure, highlighting a need to consider microstructural alterations to cranial bone when assessing the consequences of rmTBI.

Blood–brain barrier disruption and ventricular enlargement are the earliest neuropathological changes in rats with repeated sub-concussive impacts over 2 weeks

Publisher: Springer Science and Business Media LLC

Date: 29-04-2021

DOI: 10.1038/S41598-021-88854-9

Abstract: Repeated sub-concussive impact (e.g . soccer ball heading), a significantly lighter form of mild traumatic brain injury, is increasingly suggested to cumulatively alter brain structure and compromise neurobehavioural function in the long-term. However, the underlying mechanisms whereby repeated long-term sub-concussion induces cerebral structural and neurobehavioural changes are currently unknown. Here, we utilised an established rat model to investigate the effects of repeated sub-concussion on size of lateral ventricles, cerebrovascular blood–brain barrier (BBB) integrity, neuroinflammation, oxidative stress, and biochemical distribution. Following repeated sub-concussion 3 days per week for 2 weeks, the rats showed significantly enlarged lateral ventricles compared with the rats receiving sham-only procedure. The sub-concussive rats also presented significant BBB dysfunction in the cerebral cortex and hippoc al formation, whilst neuromotor function assessed by beamwalk and rotarod tests were comparable to the sham rats. Immunofluorescent and spectroscopic microscopy analyses revealed no significant changes in neuroinflammation, oxidative stress, lipid distribution or protein aggregation, within the hippoc us and cortex. These data collectively indicate that repeated sub-concussion for 2 weeks induce significant ventriculomegaly and BBB disruption, preceding neuromotor deficits.

Acute Cellular and Functional Changes With a Combinatorial Treatment of Ion Channel Inhibitors Following Spinal Cord Injury

Publisher: Frontiers Media SA

Date: 25-06-2020

DOI: 10.3389/FNMOL.2020.00085

Matrix metalloproteinases can facilitate the heparanase-induced promotion of phenotypic change in vascular smooth muscle cells

Publisher: Elsevier BV

Date: 07-1999

DOI: 10.1016/S0021-9150(99)00019-2

Abstract: Previous studies from this laboratory have shown that degradation of heparan sulphate proteoglycan by both living macrophages and macrophage lysosomal heparanase induces phenotypic change of vascular smooth muscle cells (SMC) from a high volume fraction of myofilaments (V(v)myo) to a low V(v)myo [C bell et al. Exp Cell Res 1992 200: 156-167]. The aim of this study was to determine whether matrix metalloproteinase (MMP) activity is also involved in the induction of SMC phenotypic change by macrophages. A specific inhibitor of MMPs (BB94) was able to block macrophage-induced SMC phenotypic change and subsequent DNA synthesis in freshly dispersed SMC seeded in primary culture at confluent density. The inhibitor did not block these SMC changes when SMC were seeded at low density without macrophages nor did it block heparanase activity directly. We also determined whether heparanase and MMP activities are upregulated together in vivo. Artery homogenates were analysed in a heparanase enzyme assay and for MMPs using zymograms. Increased heparanase activity was observed 3-14 days following balloon catheter injury of rabbit carotid arteries, and returned to control levels 6 weeks after injury. Active MMP2 was induced with heparanase after injury. MMP9 induction was also apparent 6 h after injury. Immunohistology on sections of these arteries showed the presence of MMPI1, 2, 3 and 9 with these MMPs being strongly induced in the intima 7 days after balloon catheter injury. Both heparanase and MMP activities were also present in human end-stage complex lesions from coronary arteries, carotid endarterectomies and abdominal aortic aneurysms. Because MMPs and heparanase are expressed at the same time, it is possible that MMPs facilitate heparanase activity in promotion of phenotypic modulation of SMC in vivo during neointimal thickening following injury and in atherosclerotic lesions.

The role of glutamine and glucose analogues in metabolic inhibition of human myeloid leukaemia In vitro

Publisher: Elsevier BV

Date: 1988

DOI: 10.1016/0020-711X(88)90303-5

Abstract: 1. Glutamine analogues L-[alpha S,5S]-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (acivicin) and 6-diazo-5-oxo-L-norleucine (DON) have been shown to possess cytotoxic activity against a wide variety of animal and human xenografted solid tumours, however their potential in man has been limited by toxicity. 2. We have analysed the effects of acivicin and DON on glutamine utilization to determine whether the reason for the disappointing therapeutic profile is solely due to the inefficient inhibition of glutamine metabolism. 3. Human myeloid leukaemic cells treated with acivicin inhibited ribonucleotide biosynthesis but not energy production via glutaminolysis and had little effect on viability, whereas treatment with DON inhibited both ribonucleotide biosynthesis and glutamine oxidation and resulted in reduced viability. 4. Treatment of the myeloid leukaemic cells with the glucose analogue 2-deoxy-D-glucose in addition to DON potentiated the inhibition of de novo nucleotide biosynthesis, glutaminolysis and glycolysis, and caused a further reduction in cell viability. 5. These results provide further support for the essential role of glutamine in cellular metabolism, and indicate that use of the glutamine analogue DON in the treatment of acute myeloid leukaemia may be more clinically effective if used in combination with 2-deoxy-D-glucose.

Specific combinations of ion channel inhibitors reduce excessive Ca²⁺influx as a consequence of oxidative stress and increase neuronal and glial cell viability in vitro

Publisher: Elsevier BV

Date: 12-2016

DOI: 10.1016/J.NEUROSCIENCE.2016.10.005

Abstract: Combinations of Ca

Paranode Abnormalities and Oxidative Stress in Optic Nerve Vulnerable to Secondary Degeneration: Modulation by 670 nm Light Treatment

Publisher: Public Library of Science (PLoS)

Date: 19-06-2013

DOI: 10.1371/JOURNAL.PONE.0066448

Three Ca2+ channel inhibitors in combination limit chronic secondary degeneration following neurotrauma

Publisher: Elsevier BV

Date: 12-2013

DOI: 10.1016/J.NEUROPHARM.2013.07.034

Abstract: Following neurotrauma, cells beyond the initial trauma site undergo secondary degeneration, with excess Ca2+ a likely trigger for loss of neurons, compact myelin and function. Treatment using inhibitors of specific Ca2+ channels has shown promise in preclinical studies, but clinical trials have been disappointing and combinatorial approaches are needed. We assessed efficacy of multiple combinations of three Ca2+ channel inhibitors at reducing secondary degeneration following partial optic nerve transection in rat. We used lomerizine to inhibit voltage gated Ca2+ channels oxidised adenosine-triphosphate (oxATP) to inhibit purinergic P2X7 receptors and/or 2-[7-(1H-imidazol-1-yl)-6-nitro-2,3-dioxo-1,2,3,4-tetrahydro quinoxalin-1-yl]acetic acid (INQ) to inhibit Ca2+ permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. Only the three Ca2+ channel inhibitors delivered in combination significantly preserved visual function, as assessed using the optokinetic nystagmus visual reflex, at 3 months after injury. Preservation of retinal ganglion cells was partial and is unlikely to have accounted for differential effects on function. A range of the Ca2+ channel inhibitor combinations prevented swelling of optic nerve vulnerable to secondary degeneration. Each of the treatments involving lomerizine significantly increased the proportion of axons with normal compact myelin. Nevertheless, limiting decompaction of myelin was not sufficient for preservation of function in our model. Multiple combinations of Ca2+ channel inhibitors reduced formation of atypical node aranode complexes outcomes were not associated with preservation of visual function. However, prevention of lengthening of the paranodal gap that was only achieved by treatment with the three Ca2+ channel inhibitors in combination was an important additional effect that likely contributed to the associated preservation of the optokinetic reflex using this combinatorial treatment strategy.

Structural requirements for anti-oxidant activity of calix[n]arenes and their associated anti-bacterial activity

Publisher: Royal Society of Chemistry (RSC)

Date: 2015

DOI: 10.1039/C4CC08576K

Abstract: We define the structural requirements for antioxidant activity of calix[ n ]arenes and relate these findings to the differential antibacterial activity of these calix[ n ]arenes against Gram+ and Gram− bacteria.

Comparison of ion channel inhibitor combinations for limiting secondary degeneration following partial optic nerve transection

Publisher: Springer Science and Business Media LLC

Date: 26-10-2019

DOI: 10.1007/S00221-018-5414-0

Abstract: Following neurotrauma, secondary degeneration of neurons and glia adjacent to the injury leads to further functional loss. A combination of ion channel inhibitors (lomerizine + oxATP + YM872) has been shown to be effective at limiting structural and functional loss due to secondary degeneration. Here we assess efficacy of the combination where oxATP is replaced with Brilliant Blue G (BBG), a more clinically applicable P2X

Early Proliferation Does Not Prevent the Loss of Oligodendrocyte Progenitor Cells during the Chronic Phase of Secondary Degeneration in a CNS White Matter Tract

Publisher: Public Library of Science (PLoS)

Date: 11-06-2013

DOI: 10.1371/JOURNAL.PONE.0065710

Angiostatin formation involves disulfide bond reduction and proteolysis in kringle 5 of plasmin

Publisher: Elsevier BV

Date: 03-1999

DOI: 10.1074/JBC.274.13.8910

Near infrared light reduces oxidative stress and preserves function in CNS tissue vulnerable to secondary degeneration following partial transection of the optic nerve

Publisher: Mary Ann Liebert Inc

Date: 11-2010

DOI: 10.1089/NEU.2010.1426

Abstract: Traumatic injury to the central nervous system (CNS) is accompanied by the spreading damage of secondary degeneration, resulting in further loss of neurons and function. Partial transection of the optic nerve (ON) has been used as a model of secondary degeneration, in which axons of retinal ganglion cells in the ventral ON are spared from initial dorsal injury, but are vulnerable to secondary degeneration. We have recently demonstrated that early after partial ON injury, oxidative stress spreads through the ventral ON vulnerable to secondary degeneration via astrocytes, and persists in the nerve in aggregates of cellular debris. In this study, we show that diffuse transcranial irradiation of the injury site with far red to near infrared (NIR) light (WARP 10 LED array, center wavelength 670 nm, irradiance 252 W/m(-2), 30 min exposure), as opposed to perception of light at this wavelength, reduced oxidative stress in areas of the ON vulnerable to secondary degeneration following partial injury. The WARP 10 NIR light treatment also prevented increases in NG-2-immunopositive oligodendrocyte precursor cells (OPCs) that occurred in ventral ON as a result of partial ON transection. Importantly, normal visual function was restored by NIR light treatment with the WARP 10 LED array, as assessed using optokinetic nystagmus and the Y-maze pattern discrimination task. To our knowledge, this is the first demonstration that 670-nm NIR light can reduce oxidative stress and improve function in the CNS following traumatic injury in vivo.

Spinal Dorsal Horn Cell Receptive Field Size is Increased in Adult Rats Following Neonatal Hindpaw Skin Injury

Publisher: Wiley

Date: 07-2003

DOI: 10.1113/JPHYSIOL.2003.043661

Nanoparticle-mediated internalisation and release of a calcium channel blocker

Publisher: Royal Society of Chemistry (RSC)

Date: 2012

DOI: 10.1039/C2RA21058D

Intravitreal application of AAV-BDNF or mutant AAV-CRMP2 protects retinal ganglion cells and stabilizes axons and myelin after partial optic nerve injury

Publisher: Elsevier BV

Date: 04-2020

DOI: 10.1016/J.EXPNEUROL.2019.113167

Abstract: Secondary degeneration following an initial injury to the central nervous system (CNS) results in increased tissue loss and is associated with increasing functional impairment. Unilateral partial dorsal transection of the adult rat optic nerve (ON) has proved to be a useful experimental model in which to study factors that contribute to secondary degenerative events. Using this injury model, we here quantified the protective effects of intravitreally administered bi-cistronic adeno-associated viral (AAV2) vectors encoding either brain derived neurotrophic factor (BDNF) or a mutant, phospho-resistant, version of collapsin response mediator protein 2 (CRMP2T555A) on retinal ganglion cells (RGCs), their axons, and associated myelin. To test for potential synergistic interactions, some animals received combined injections of both vectors. Three months post-injury, all treatments maintained RGC numbers in central retina, but only AAV2-BDNF significantly protected ventrally located RGCs exclusively vulnerable to secondary degeneration. Behaviourally, treatments that involved AAV2-BDNF significantly restored the number of smooth-pursuit phases of optokinetic nystagmus. While all therapeutic regimens preserved axonal density and proportions of typical complexes, including heminodes and single nodes, BDNF treatments were generally more effective in maintaining the length of the node of Ranvier in myelin surrounding ventral ON axons after injury. Both AAV2-BDNF and AAV2-CRMP2T555A prevented injury-induced changes in G-ratio and overall myelin thickness, but only AAV2-BDNF administration protected against large-scale myelin decompaction in ventral ON. In summary, in a model of secondary CNS degeneration, both BDNF and CRMP2T555A vectors were neuroprotective, however different efficacies were observed for these overexpressed proteins in the retina and ON, suggesting disparate cellular and molecular targets driving responses for neural repair. The potential use of these vectors to treat other CNS injuries and pathologies is discussed.

Intracellular speciation of gold nanorods alters the conformational dynamics of genomic DNA.

Publisher: Springer Science and Business Media LLC

Date: 08-10-2018

DOI: 10.1038/S41565-018-0272-2

Abstract: Gold nanorods are one of the most widely explored inorganic materials in nanomedicine for diagnostics, therapeutics and sensing

Chronic Swelling and Abnormal Myelination during Secondary Degeneration after Partial Injury to a Central Nervous System Tract

Publisher: Mary Ann Liebert Inc

Date: 06-2011

DOI: 10.1089/NEU.2010.1665

Abstract: Secondary degeneration is a serious consequence of traumatic injury to the central nervous system (CNS) and involves the progressive loss of neurons and function. However, while disruption to myelin has been observed in spared axons, the ultrastructural abnormalities that occur in myelin and axons spatially separated from the primary injury and susceptible exclusively to secondary degeneration are unknown. We used a model of secondary degeneration in which the dorsal aspect of rat optic nerve (ON) was transected leaving the central/ventral ON undamaged, but vulnerable to secondary degeneration. Transmission electron microscopy of the central/ventral ON at 1 and 3 months was used to quantify secondary changes in axon diameter, myelin sheath thickness and morphology, compared to normal animals. Three months after partial ON transection, cross-sectional nerve area at the injury site was increased (p ≤ 0.05), and changes in axons and myelin sheaths were detected in the central/ventral ON. Although myelin sheath thickness remained normal at both time points, average axon diameter significantly increased at 3 months. The density of the total axon population was decreased by 1 month, reflecting loss of retinal ganglion cells as previously published, with a decrease in the density of normally-myelinated axons, but an increase in unmyelinated axon density (p ≤ 0.05). Myelin basic protein immunoreactivity and fluoromyelin staining were also significantly reduced. Within four subpopulations of abnormally-myelinated axons, there was: no change in lightly-myelinated axons an increase in axons with excessive myelination (at 1 month) and an increase in the density of axons with partial and fully-decompacted myelin (at 3 months, p ≤ 0.05). Chronic axon swelling and myelin sheath compaction defects are features of secondary degeneration, and may contribute to the reported loss of ON function following partial transection.

Novel Hydrophilic Copolymer-Based Nanoparticle Enhances the Therapeutic Efficiency of Doxorubicin in Cultured MCF-7 Cells

Publisher: American Chemical Society (ACS)

Date: 11-10-2019

DOI: 10.1021/ACSOMEGA.8B02894

In vivo imaging and biodistribution of multimodal polymeric nanoparticles delivered to the optic nerve

Publisher: Wiley

Date: 13-03-2012

DOI: 10.1002/SMLL.201102648

Abstract: The use of nanoparticles for targeted delivery of therapeutic agents to sites of injury or disease in the central nervous system (CNS) holds great promise. However, the biodistribution of nanoparticles following in vivo administration is often unknown, and concerns have been raised regarding potential toxicity. Using poly(glycidyl methacrylate) (PGMA) nanoparticles coated with polyethylenimine (PEI) and containing superparamagnetic iron oxide nanoparticles as a magnetic resonance imaging (MRI) contrast agent and rhodamine B as a fluorophore, whole animal MRI and fluorescence analyses are used to demonstrate that these nanoparticles (NP) remain close to the site of injection into a partial injury of the optic nerve, a CNS white matter tract. In addition, some of these NP enter axons and are transported to parent neuronal somata. NP also remain in the eye following intravitreal injection, a non-injury model. Considerable infiltration of activated microglia/macrophages occurs in both models. Using magnetic concentration and fluorescence visualization of tissue homogenates, no dissemination of the NP into peripheral tissues is observed. Histopathological analysis reveals no toxicity in organs other than at the injection sites. Multifunctional nanoparticles may be a useful mechanism to deliver therapeutic agents to the injury site and somata of injured CNS neurons and thus may be of therapeutic value following brain or spinal cord trauma.

Inhibition of phenotype modulation, growth, and migration of vascular smooth muscle cells by a guanosine-rich 30-mer phosphorothioate oligodeoxynucleotide

Publisher: Wiley

Date: 09-1997

DOI: 10.1006/CBIR.1997.0189

Abstract: The testing of a 30-mer dG-rich phosphorothioate oligodeoxynucleotide (LG4PS) for effects on the behaviour of vascular smooth muscle cells (VSMC) in vitro and in vivo is described. LG4PS at 0.3 microM inhibited significantly the phenotype modulation of freshly isolated rabbit VSMC, and cell outgrowth from pig aortic explants was inhibited approximately 80% by 5 microM LG4PS. The growth of proliferating rabbit and pig VSMC was inhibited approximately 70% by 0.3 microM and 5 microM LG4PS, respectively. Though less marked, the antiproliferative effects of LG4PS on human VSMC were comparable to those obtained with heparin. The cytotoxic effects of LG4PS on VSMC in vitro were low. Despite these promising results, adventitial application of 2-200 nmol LG4PS in pluronic gel failed to reduce vascular hyperplasia in balloon-injured rabbit carotid arteries, and the highest dose caused extensive mortality.

Redox control of exofacial protein thiols/disulfides by protein disulfide isomerase.

Publisher: Elsevier BV

Date: 1999

DOI: 10.1074/JBC.274.4.2416

A Neurogenic Perspective of Sarcopenia: Time Course Study of Sciatic Nerves From Aging Mice

Publisher: Oxford University Press (OUP)

Date: 30-03-2016

DOI: 10.1093/JNEN/NLW019

Abstract: To elucidate the neural basis for age-related sarcopenia, we quantified morphologic and molecular changes within sciatic nerves of aging male and female C57BL/6J mice aged between 3 and 27 months using immunoblotting, immunohistochemistry, and electron microscopy. Protein analyses by immunoblotting of nerves of male mice aged 4, 15, 18, 22, and 24 months showed increased levels of heavy chain SMI-32-positive neurofilaments, vimentin, tau5, choline acetyltransferase (ChAT), and p62 by 18-22 months. Similar protein increases were seen in 26-month-old compared with 3-month-old female mice. Immunostaining of longitudinal sections of old (27-month-old) male sciatic nerves revealed intense staining for tau5 and p62 that was increased compared with that at 3 months, but there were decreased numbers of axon profiles stained for ChAT or isolectin B4 (motor and sensory axons, respectively). Ultrastructural analysis revealed electron-dense aggregates within axons in peripheral nerves of old male mice the proportion of axons that contained aggregates more than doubled between 15 and 27 months. Overall, the observed age-related accumulation of many proteins from about 18 months of age onward suggests impaired mechanisms for axonal transport and protein turnover. These peripheral nerve changes may contribute to the morphological and functional muscle deficits associated with sarcopenia.

Curtin University

Location: Australia

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Connectivity

Location: Australia

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Perron Institute For Neurological And Translational Science

Location: Australia

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Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0989788

Start Date: 01-2009

End Date: 01-2010

Amount: $108,481.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE200100122

Start Date: 08-2020

End Date: 08-2021

Amount: $620,000.00

Funder: Australian Research Council