84 research outputs found
Neuronal influences are necessary to produce mitochondrial co-localization with glutamate transporters in astrocytes.
yesAbstract
Recent evidence suggests that the predominant astrocyte
glutamate transporter, GLT-1/ Excitatory Amino Acid Transporter
2 (EAAT2) is associated with mitochondria. We used
primary cultures of mouse astrocytes to assess co-localization
of GLT-1 with mitochondria, and tested whether the interaction
was dependent on neurons, actin polymerization or the kinesin
adaptor, TRAK2. Mouse primary astrocytes were transfected
with constructs expressing V5-tagged GLT-1, pDsRed1-Mito
with and without dominant negative TRAK2. Astrocytes were
visualized using confocal microscopy and co-localization was
quantified using Volocity software. Image analysis of confocal
z-stacks revealed no co-localization between mitochondria
and GLT-1 in pure astrocyte cultures. Co-culture of astrocytes
with primary mouse cortical neurons revealed more mitochondria
in processes and a positive correlation between mitochondria
and GLT-1. This co-localization was not further
enhanced after neuronal depolarization induced by 1 h treatment
with 15 mM K+. In pure astrocytes, a rho kinase inhibitor,
Y27632 caused the distribution of mitochondria to astrocyte
processes without enhancing GLT-1/mitochondrial co-localization,
however, in co-cultures, Y27632 abolished mitochondrial:
GLT-1 co-localization. Disrupting potential mitochondrial:
kinesin interactions using dominant negative TRAK2 did not
alter GLT-1 distribution or GLT-1: mitochondrial co-localization.
We conclude that the association between GLT-1 and
mitochondria is modest, is driven by synaptic activity and
dependent on polymerized actin filaments.
Mitochondria have limited co-localization with the glutamate transporter GLT-1 in primary astrocytes in culture. Few mitochondria are in the fine processes where GLT-1 is abundant. It is necessary to culture astrocytes with neurones to drive a significant level of co-localization, but co-localization is not further altered by depolarization, manipulating sodium ion gradients or Na/K ATPase activity
Benthic habitat mapping in coastal waters of south–east Australia
The Victorian Marine Mapping Project will improve knowledge on the location, spatial distribution, condition and extent of marine habitats and associated biodiversity in Victorian State waters. This information will guide informed decision making, enable priority setting, and assist in targeted natural resource management planning. This project entails benthic habitat mapping over 500 square kilometers of Victorian State waters using multibeam sonar, towed video and image classification techniques. Information collected includes seafloor topography, seafloor softness and hardness (reflectivity), and information on geology and benthic flora and fauna assemblages collectively comprising habitat. Computerized semi-automated classification techniques are also being developed to provide a cost effective approach to rapid mapping and assessment of coastal habitats.Habitat mapping is important for understanding and communicating the distribution of natural values within the marine environment. The coastal fringe of Victoria encompasses a rich and diverse ecosystem representative of coastal waters of South-east Australia. To date, extensive knowledge of these systems is limited due to the lack of available data. Knowledge of the distribution and extent of habitat is required to target management activities most effectively, and provide the basis to monitor and report on their status in the future.<br /
Immunoablation of cells expressing the NG2 chondroitin sulphate proteoglycan
YesExpression of the transmembrane NG2 chondroitin sulphate proteoglycan (CSPG) defines a distinct population
of NG2-glia. NG2-glia serve as a regenerative pool of oligodendrocyte progenitor cells in the adult central
nervous system (CNS), which is important for demyelinating diseases such as multiple sclerosis, and are a major
component of the glial scar that inhibits axon regeneration after CNS injury. In addition, NG2-glia form unique
neuron–glial synapses with unresolved functions. However, to date it has proven difficult to study the
importance of NG2-glia in any of these functions using conventional transgenic NG2 ‘knockout’ mice. To
overcome this, we aimed to determine whether NG2-glia can be targeted using an immunotoxin approach. We
demonstrate that incubation in primary anti-NG2 antibody in combination with secondary saporin-conjugated
antibody selectively kills NG2-expressing cells in vitro. In addition, we provide evidence that the same protocol
induces the loss of NG2-glia without affecting astrocyte or neuronal numbers in cerebellar brain slices from
postnatal mice. This study shows that targeting the NG2 CSPG with immunotoxins is an effective and selective
means for killing NG2-glia, which has important implications for studying the functions of these enigmatic cells
both in the normal CNS, and in demyelination and degeneration
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Sonic hedgehog signalling mediates astrocyte crosstalk with neurons to confer neuroprotection
Sonic hedgehog (SHH) is a glycoprotein associated with development that is also expressed in the adult CNS and released after brain injury. Since the SHH receptors patched homolog-1 and Smoothened are highly expressed on astrocytes, we hypothesized that SHH regulates astrocyte function. Primary mouse cortical astrocytes derived from embryonic Swiss mouse cortices, were treated with two chemically distinct agonists of the SHH pathway, which caused astrocytes to elongate and proliferate. These changes are accompanied by decreases in the major astrocyte glutamate transporter-1 and the astrocyte intermediate filament protein glial fibrillary acidic protein. Multisite electrophysiological recordings revealed that the SHH agonist, smoothened agonist suppressed neuronal firing in astrocyte-neuron co-cultures and this was abolished by the astrocyte metabolic inhibitor ethylfluoroacetate, revealing that SHH stimulation of metabolically active astrocytes influences neuronal firing. Using three-dimensional co-culture, MAP2 western blotting and immunohistochemistry, we show that SHH-stimulated astrocytes protect neurons from kainate-induced cell death. Altogether the results show that SHH regulation of astrocyte function represents an endogenous neuroprotective mechanism
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Endoplasmic reticulum stress signalling induces casein kinase 1-dependent formation of cytosolic TDP-43 Inclusions in motor neuron-like cells
YesMotor neuron disease (MND) is a progressive neurodegenerative disease with no effective treatment. One of the principal pathological hallmarks is the deposition of TAR DNA binding protein 43 (TDP-43) in cytoplasmic inclusions. TDP-43 aggregation occurs in both familial and sporadic MND; however, the mechanism of endogenous TDP-43 aggregation in disease is incompletely understood. This study focused on the induction of cytoplasmic accumulation of endogenous TDP-43 in the motor neuronal cell line NSC-34. The endoplasmic reticulum (ER) stressor tunicamycin induced casein kinase 1 (CK1)-dependent cytoplasmic accumulation of endogenous TDP-43 in differentiated NSC-34 cells, as seen by immunocytochemistry. Immunoblotting showed that induction of ER stress had no effect on abundance of TDP-43 or phosphorylated TDP-43 in the NP-40/RIPA soluble fraction. However, there were significant increases in abundance of TDP-43 and phosphorylated TDP-43 in the NP-40/RIPA-insoluble, urea-soluble fraction, including high molecular weight species. In all cases, these increases were lowered by CK1 inhibition. Thus ER stress signalling, as induced by tunicamycin, causes CK1-dependent phosphorylation of TDP-43 and its consequent cytosolic accumulation.Funded by a biomedical research grant from the Motor Neurone Disease Association (ref Rattray/Apr15/837-791). The Bioimaging Facility microscopes used in this study were purchased with grants from BBSRC, Wellcome Trust and the University of Manchester Strategic Fund
An exploration of the impact of SARS-CoV-2 (COVID-19) restrictions on marginalised groups in the UK
YesBackground: To contain the spread of COVID-19 within the UK over the past year, there have been a series of local and national lockdowns. These restrictions are likely to have impacted upon the health and well-being of marginalised groups who rely on now closed social and community support services to stay healthy. An understanding of the experiences of marginalised people is important; therefore, this study aimed to explore the impact of the COVID-19 restrictions on the health and well-being of marginalised groups in the UK.
Methods: In summer 2020, a rapid telephone survey was conducted by trained, trusted volunteers with 76 participants who were from marginalised groups. As part of this survey, 64 participants consented to describe their experience of lockdown. These case studies were thematically analysed to identify patterns of meaning.
Results: Findings indicate that lockdown led to the deterioration of health of participants, impacted adversely on their socio-economic positions and affected access to food and essential supplies. In addition, government public health messaging was considered confusing and inadequate.
Conclusions: This study highlights the need for pathways into services which support marginalised groups to remain accessible during periods of restrictions and essential supplies and food to be mapped and protected for marginalised individuals within our local communities.NHS England; Improvemen
An Analysis of Pharmacogenomic-Guided Pathways and Their Effect on Medication Changes and Hospital Admissions: A Systematic Review and Meta-Analysis
Ninety-five percent of the population are estimated to carry at least one genetic variant that is discordant with at least one medication. Pharmacogenomic (PGx) testing has the potential to identify patients with genetic variants that puts them at risk of adverse drug reactions and sub-optimal therapy. Predicting a patient's response to medications could support the safe management of medications and reduce hospitalization. These benefits can only be realized if prescribing clinicians make the medication changes prompted by PGx test results. This review examines the current evidence on the impact PGx testing has on hospital admissions and whether it prompts medication changes. A systematic search was performed in three databases (Medline, CINAHL and EMBASE) to search all the relevant studies published up to the year 2020, comparing hospitalization rates and medication changes amongst PGx tested patients with patients receiving treatment-as-usual (TAU). Data extracted from full texts were narratively synthesized using a process model developed from the included studies, to derive themes associated to a suggested workflow for PGx-guided care and its expected benefit for medications optimization and hospitalization. A meta-analysis was undertaken on all the studies that report the number of PGx tested patients that had medication change(s) and the number of PGx tested patients that were hospitalized, compared to participants that received TAU. The search strategy identified 5 hospitalization themed studies and 5 medication change themed studies for analysis. The meta-analysis showed that medication changes occurred significantly more frequently in the PGx tested arm across 4 of 5 studies. Meta-analysis showed that all-cause hospitalization occurred significantly less frequently in the PGx tested arm than the TAU. The results show proof of concept for the use of PGx in prescribing that produces patient benefit. However, the review also highlights the opportunities and evidence gaps that are important when considering the introduction of PGx into health systems; namely patient involvement in PGx prescribing decisions, thus a better understanding of the perspective of patients and prescribers. We highlight the opportunities and evidence gaps that are important when considering the introduction of PGx into health systems
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Patient Perspectives on Factors Affecting Direct Oral Anticoagulant Use for Stroke Prevention in Atrial Fibrillation
YesIntroduction: Oral anticoagulant therapy choices for patients with atrial fibrillation (AF) expanded in the last decade with the introduction of direct oral anticoagulants (DOAC). However, the implementation of DOACs was slow and varied across different health economies in England. There is limited evidence on the patient role in the uptake of new medicines, including DOACs, apart from considering their demographic and clinical characteristics. Hence, this study aimed to address the gap by exploring the view of patients with AF on factors affecting DOAC use.
Methods: A qualitative study using semi-structured interviews was conducted in three health economies in the North of England. Adult patients (>18 years) diagnosed with non-valvular AF, prescribed an oral anticoagulant (vitamin K antagonist or DOAC), and able to give written consent were recruited. Data were collected between August 2018 and April 2019. Audio recorded interviews were transcribed verbatim and analyzed using the framework method.
Results: Four themes with eleven subthemes discussed identified factors affecting the use of DOACs. They were linked to limited healthcare financial and workforce resources, patient involvement in decision-making, patient knowledge about DOACs, safety concerns about oral anticoagulants, and oral anticoagulant therapy impact on patients' daily lives. Lack of a) opportunities to voice patient preferences and b) information on available therapy options resulted in some patients experiencing difficulties with the prescribed therapy. This was reported to cause negative impact on their daily lives, adherence, and overall satisfaction with the therapy.
Conclusion: Greater patient involvement in decision-making could prevent and resolve difficulties encountered by some patients and potentially improve outcomes plus increase the uptake of DOACs.Pharmacy Research UK (PRUK-2018-GA-1-KM) and Leeds Teaching Hospitals NHS Trus
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Dietary levels of pure flavonoids improve spatial memory performance and increase hippocampal brain-derived neurotrophic factor.
Evidence suggests that flavonoid-rich foods are capable of inducing improvements in memory and cognition in animals and humans. However, there is a lack of clarity concerning whether flavonoids are the causal agents in inducing such behavioral responses. Here we show that supplementation with pure anthocyanins or pure flavanols for 6 weeks, at levels similar to that found in blueberry (2% w/w), results in an enhancement of spatial memory in 18 month old rats. Pure flavanols and pure anthocyanins were observed to induce significant improvements in spatial working memory (p = 0.002 and p = 0.006 respectively), to a similar extent to that following blueberry supplementation (p = 0.002). These behavioral changes were paralleled by increases in hippocampal brain-derived neurotrophic factor (R = 0.46, p<0.01), suggesting a common mechanism for the enhancement of memory. However, unlike protein levels of BDNF, the regional enhancement of BDNF mRNA expression in the hippocampus appeared to be predominantly enhanced by anthocyanins. Our data support the claim that flavonoids are likely causal agents in mediating the cognitive effects of flavonoid-rich foods
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