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Żukowska J, Moss SJ, Subramanian V, Acharya KR. Molecular basis of selective amyloid-β degrading enzymes in Alzheimer's disease. FEBS J 2023. [PMID: 37622248 DOI: 10.1111/febs.16939] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 07/31/2023] [Accepted: 08/22/2023] [Indexed: 08/26/2023]
Abstract
The accumulation of the small 42-residue long peptide amyloid-β (Aβ) has been proposed as a major trigger for the development of Alzheimer's disease (AD). Within the brain, the concentration of Aβ peptide is tightly controlled through production and clearance mechanisms. Substantial experimental evidence now shows that reduced levels of Aβ clearance are present in individuals living with AD. This accumulation of Aβ can lead to the formation of large aggregated amyloid plaques-one of two detectable hallmarks of the disease. Aβ-degrading enzymes (ADEs) are major players in the clearance of Aβ. Stimulating ADE activity or expression, in order to compensate for the decreased clearance in the AD phenotype, provides a promising therapeutic target. It has been reported in mice that upregulation of ADEs can reduce the levels of Aβ peptide and amyloid plaques-in some cases, this led to improved cognitive function. Among several known ADEs, neprilysin (NEP), endothelin-converting enzyme-1 (ECE-1), insulin degrading enzyme (IDE) and angiotensin-1 converting enzyme (ACE) from the zinc metalloprotease family have been identified as important. These ADEs have the capacity to digest soluble Aβ which, in turn, cannot form the toxic oligomeric species. While they are known for their amyloid degradation, they exhibit complexity through promiscuous nature and a broad range of substrates that they can degrade. This review highlights current structural and functional understanding of these key ADEs, giving some insight into the molecular interactions that leads to the hydrolysis of peptide substrates, the crucial tasks performed by them and the potential for therapeutic use in the future.
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Wilkinson K, Day J, Thompson-Coon J, Goodwin V, Liabo K, Coxon G, Cox G, Marriott C, Lang IA. A realist evaluation of a collaborative model to support research co-production in long-term care settings in England: the ExCHANGE protocol. Res Involv Engagem 2021; 7:18. [PMID: 33743827 PMCID: PMC7980357 DOI: 10.1186/s40900-021-00257-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 02/22/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Collaborative working between academic institutions and those who provide health and social care has been identified as integral in order to produce acceptable, relevant, and timely research, and for outputs to be useful and practical to implement. The ExCHANGE Collaboration aims to bring together researchers and people working, living in and visiting care homes to build capacity, share and mobilise knowledge, and identify key areas for future research. This paper describes an embedded, formative, realist and theory-driven evaluation which aims to gather information about how successful the ExCHANGE Collaboration is perceived to be in achieving its aims. An existing realist programme theory from the literature - Closer Collaboration - will be supplemented by two substantive theories: Co-production and Knowledge Brokering. This will result in an initial programme theory which will be tested by this formative evaluation to refine understanding of how the ExCHANGE Collaboration works. METHODS The evaluation will employ mixed qualitative methods, including: analysis of documents such as feedback forms, Knowledge Broker journal/diary, event attendance records, risk and issues logs and other relevant paperwork gathered as part of project delivery; observations of events/activities; and interviews with care home providers and staff, care home residents, residents' family members, and researchers who are involved in the project (both project design/delivery, and also attendance or involvement in project activities/events). Framework Analysis will be used to interpret the data collected; analysis will be strategic, by focusing on particular key areas of importance in the developing theory of how the ExCHANGE Collaboration might achieve change. RESULTS The results of this study are expected to be published in 2022. DISCUSSION This evaluation will investigate how successful the ExCHANGE Collaboration is perceived to be in achieving its aims, in what way, in which contexts, and how this may differ for those involved. It will do this by testing an initial programme theory about how the collaboration works, for whom, under which circumstances, and in what way. Findings will be shared through written publication, an end of project learning event for those involved/interested in the project, and a lay summary to be made publically available.
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Affiliation(s)
- K Wilkinson
- University of Exeter, College of Medicine and Health, St Luke's Campus, Heavitree Road, Exeter, EX1 2LU, UK.
| | - J Day
- University of Exeter, College of Medicine and Health, St Luke's Campus, Heavitree Road, Exeter, EX1 2LU, UK
| | - J Thompson-Coon
- University of Exeter, College of Medicine and Health, St Luke's Campus, Heavitree Road, Exeter, EX1 2LU, UK
| | - V Goodwin
- University of Exeter, College of Medicine and Health, St Luke's Campus, Heavitree Road, Exeter, EX1 2LU, UK
| | - K Liabo
- University of Exeter, College of Medicine and Health, St Luke's Campus, Heavitree Road, Exeter, EX1 2LU, UK
| | - G Coxon
- Classic Care Homes (Devon) Ltd, Pottles Court, Days Pottles Lane, Exminster, Devon, EX6 8RL, UK
| | - G Cox
- Southern Healthcare (Wessex) Ltd, Sefton Hall, 11 Plantation Terrace, Dawlish, Devon, EX7 9DS, UK
| | - C Marriott
- The Peninsula Public Engagement Group (PenPEG) member, University of Exeter, College of Medicine and Health, St Luke's Campus, Heavitree Road, Exeter, EX1 2LU, UK
| | - I A Lang
- University of Exeter, College of Medicine and Health, St Luke's Campus, Heavitree Road, Exeter, EX1 2LU, UK
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Abstract
COVID-19 is primarily a respiratory disease but up to two thirds of hospitalised patients show evidence of central nervous system (CNS) damage, predominantly ischaemic, in some cases haemorrhagic and occasionally encephalitic. It is unclear how much of the ischaemic damage is mediated by direct or inflammatory effects of virus on the CNS vasculature and how much is secondary to extracranial cardiorespiratory disease. Limited data suggest that the causative SARS-CoV-2 virus may enter the CNS via the nasal mucosa and olfactory fibres, or by haematogenous spread, and is capable of infecting endothelial cells, pericytes and probably neurons. Extracranially, SARS-CoV-2 targets endothelial cells and pericytes, causing endothelial cell dysfunction, vascular leakage and immune activation, sometimes leading to disseminated intravascular coagulation. It remains to be confirmed whether endothelial cells and pericytes in the cerebral vasculature are similarly targeted. Several aspects of COVID-19 are likely to impact on cognition. Cerebral white matter is particularly vulnerable to ischaemic damage in COVID-19 and is also critically important for cognitive function. There is accumulating evidence that cerebral hypoperfusion accelerates amyloid-β (Aβ) accumulation and is linked to tau and TDP-43 pathology, and by inducing phosphorylation of α-synuclein at serine-129, ischaemia may also increase the risk of development of Lewy body disease. Current therapies for COVID-19 are understandably focused on supporting respiratory function, preventing thrombosis and reducing immune activation. Since angiotensin-converting enzyme (ACE)-2 is a receptor for SARS-CoV-2, and ACE inhibitors and angiotensin receptor blockers are predicted to increase ACE-2 expression, it was initially feared that their use might exacerbate COVID-19. Recent meta-analyses have instead suggested that these medications are protective. This is perhaps because SARS-CoV-2 entry may deplete ACE-2, tipping the balance towards angiotensin II-ACE-1-mediated classical RAS activation: exacerbating hypoperfusion and promoting inflammation. It may be relevant that APOE ε4 individuals, who seem to be at increased risk of COVID-19, also have lowest ACE-2 activity. COVID-19 is likely to leave an unexpected legacy of long-term neurological complications in a significant number of survivors. Cognitive follow-up of COVID-19 patients will be important, especially in patients who develop cerebrovascular and neurological complications during the acute illness.
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Affiliation(s)
- Scott Miners
- Dementia Research Group, Bristol Medical School (THS), University of Bristol, Learning & Research level 1, Southmead Hospital, Bristol, BS10 5NB, UK.
| | - Patrick G Kehoe
- Dementia Research Group, Bristol Medical School (THS), University of Bristol, Learning & Research level 1, Southmead Hospital, Bristol, BS10 5NB, UK
| | - Seth Love
- Dementia Research Group, Bristol Medical School (THS), University of Bristol, Learning & Research level 1, Southmead Hospital, Bristol, BS10 5NB, UK.
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Woodling NS, Rajasingam A, Minkley LJ, Rizzo A, Partridge L. Independent glial subtypes delay development and extend healthy lifespan upon reduced insulin-PI3K signalling. BMC Biol 2020; 18:124. [PMID: 32928209 PMCID: PMC7490873 DOI: 10.1186/s12915-020-00854-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 08/21/2020] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND The increasing age of global populations highlights the urgent need to understand the biological underpinnings of ageing. To this end, inhibition of the insulin/insulin-like signalling (IIS) pathway can extend healthy lifespan in diverse animal species, but with trade-offs including delayed development. It is possible that distinct cell types underlie effects on development and ageing; cell-type-specific strategies could therefore potentially avoid negative trade-offs when targeting diseases of ageing, including prevalent neurodegenerative diseases. The highly conserved diversity of neuronal and non-neuronal (glial) cell types in the Drosophila nervous system makes it an attractive system to address this possibility. We have thus investigated whether IIS in distinct glial cell populations differentially modulates development and lifespan in Drosophila. RESULTS We report here that glia-specific IIS inhibition, using several genetic means, delays development while extending healthy lifespan. The effects on lifespan can be recapitulated by adult-onset IIS inhibition, whereas developmental IIS inhibition is dispensable for modulation of lifespan. Notably, the effects we observe on both lifespan and development act through the PI3K branch of the IIS pathway and are dependent on the transcription factor FOXO. Finally, IIS inhibition in several glial subtypes can delay development without extending lifespan, whereas the same manipulations in astrocyte-like glia alone are sufficient to extend lifespan without altering developmental timing. CONCLUSIONS These findings reveal a role for distinct glial subpopulations in the organism-wide modulation of development and lifespan, with IIS in astrocyte-like glia contributing to lifespan modulation but not to developmental timing. Our results enable a more complete picture of the cell-type-specific effects of the IIS network, a pathway whose evolutionary conservation in humans make it tractable for therapeutic interventions. Our findings therefore underscore the necessity for cell-type-specific strategies to optimise interventions for the diseases of ageing.
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Affiliation(s)
- Nathaniel S Woodling
- Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Arjunan Rajasingam
- Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Lucy J Minkley
- Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Alberto Rizzo
- Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Linda Partridge
- Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK.
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Strasse 9b, 50931, Cologne, Germany.
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Brown A, Page TE, Daley S, Farina N, Basset T, Livingston G, Budgett J, Gallaher L, Feeney Y, Murray J, Bowling A, Knapp M, Banerjee S. Measuring the quality of life of family carers of people with dementia: development and validation of C-DEMQOL. Qual Life Res 2019; 28:2299-2310. [PMID: 31030366 PMCID: PMC6620239 DOI: 10.1007/s11136-019-02186-w] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2019] [Indexed: 11/17/2022]
Abstract
PURPOSE We aimed to address gaps identified in the evidence base and instruments available to measure the quality of life (QOL) of family carers of people with dementia, and develop a new brief, reliable, condition-specific instrument. METHODS We generated measurable domains and indicators of carer QOL from systematic literature reviews and qualitative interviews with 32 family carers and 9 support staff, and two focus groups with 6 carers and 5 staff. Statements with five tailored response options, presenting variation on the QOL continuum, were piloted (n = 25), pre-tested (n = 122) and field-tested (n = 300) in individual interviews with family carers from North London and Sussex. The best 30 questions formed the C-DEMQOL questionnaire, which was evaluated for usability, face and construct validity, reliability and convergent/discriminant validity using a range of validation measures. RESULTS C-DEMQOL was received positively by the carers. Factor analysis confirmed that C-DEMQOL sum scores are reliable in measuring overall QOL (ω = 0.97) and its five subdomains: 'meeting personal needs' (ω = 0.95); 'carer wellbeing' (ω = 0.91); 'carer-patient relationship' (ω = 0.82); 'confidence in the future' (ω = 0.90) and 'feeling supported' (ω = 0.85). The overall QOL and domain scores show the expected pattern of convergent and discriminant relationships with established measures of carer mental health, activities and dementia severity and symptoms. CONCLUSIONS The robust psychometric properties support the use of C-DEMQOL in evaluation of overall and domain-specific carer QOL; replications in independent samples and studies of responsiveness would be of value.
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Affiliation(s)
- Anna Brown
- School of Psychology, University of Kent, Canterbury, CT2 7NP, UK.
| | - Thomas E Page
- School of Psychology, University of Kent, Canterbury, CT2 7NP, UK
| | - Stephanie Daley
- Centre for Dementia Studies, Brighton and Sussex Medical School, University of Sussex, Brighton, BN1 9RY, UK
| | - Nicolas Farina
- Centre for Dementia Studies, Brighton and Sussex Medical School, University of Sussex, Brighton, BN1 9RY, UK
| | - Thurstine Basset
- Lived Experience Advisory Panel, Sussex Partnership NHS Foundation Trust, Hove, BN3 7HQ, UK
| | - Gill Livingston
- Division of Psychiatry, University College London, London, W1T 7NF, UK
| | - Jessica Budgett
- Division of Psychiatry, University College London, London, W1T 7NF, UK
| | - Laura Gallaher
- Centre for Dementia Studies, Brighton and Sussex Medical School, University of Sussex, Brighton, BN1 9RY, UK
| | - Yvonne Feeney
- Centre for Dementia Studies, Brighton and Sussex Medical School, University of Sussex, Brighton, BN1 9RY, UK
| | - Joanna Murray
- Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, SE5 8AF, UK
| | - Ann Bowling
- Health Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - Martin Knapp
- Department of Social Policy, London School of Economics, London, CT1 3LX, UK
| | - Sube Banerjee
- Centre for Dementia Studies, Brighton and Sussex Medical School, University of Sussex, Brighton, BN1 9RY, UK
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Pauls MMH, Clarke N, Trippier S, Betteridge S, Howe FA, Khan U, Kruuse C, Madigan JB, Moynihan B, Pereira AC, Rolfe D, Rostrup E, Haig CE, Barrick TR, Isaacs JD, Hainsworth AH. Perfusion by Arterial Spin labelling following Single dose Tadalafil In Small vessel disease (PASTIS): study protocol for a randomised controlled trial. Trials 2017; 18:229. [PMID: 28532471 PMCID: PMC5440904 DOI: 10.1186/s13063-017-1973-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 05/04/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cerebral small vessel disease is a common cause of vascular cognitive impairment in older people, with no licensed treatment. Cerebral blood flow is reduced in small vessel disease. Tadalafil is a widely prescribed phosphodiesterase-5 inhibitor that increases blood flow in other vascular territories. The aim of this trial is to test the hypothesis that tadalafil increases cerebral blood flow in older people with small vessel disease. METHODS/DESIGN Perfusion by Arterial Spin labelling following Single dose Tadalafil In Small vessel disease (PASTIS) is a phase II randomised double-blind crossover trial. In two visits, 7-30 days apart, participants undergo arterial spin labelling to measure cerebral blood flow and a battery of cognitive tests, pre- and post-dosing with oral tadalafil (20 mg) or placebo. SAMPLE SIZE 54 participants are required to detect a 15% increase in cerebral blood flow in subcortical white matter (p < 0.05, 90% power). Primary outcomes are cerebral blood flow in subcortical white matter and deep grey nuclei. Secondary outcomes are cortical grey matter cerebral blood flow and performance on cognitive tests (reaction time, information processing speed, digit span forwards and backwards, semantic fluency). DISCUSSION Recruitment started on 4th September 2015 and 36 participants have completed to date (19th April 2017). No serious adverse events have occurred. All participants have been recruited from one centre, St George's University Hospitals NHS Foundation Trust. TRIAL REGISTRATION European Union Clinical Trials Register: EudraCT number 2015-001235-20 . Registered on 13 May 2015.
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Affiliation(s)
- Mathilde M. H. Pauls
- Neurosciences Research Centre, Molecular and Clinical Sciences Research Institute, St George’s University of London, Cranmer Terrace, London, SW17 0RE UK
- Cell Biology and Genetics Research Centre, Molecular and Clinical Sciences Research Institute, St George’s University of London, Cranmer Terrace, London, SW17 0RE UK
- Department of Neurology, St George’s University Hospitals NHS Foundation Trust, Blackshaw Road, London, SW17 0QT UK
| | - Natasha Clarke
- Neurosciences Research Centre, Molecular and Clinical Sciences Research Institute, St George’s University of London, Cranmer Terrace, London, SW17 0RE UK
- Stroke Clinical Research Network, St George’s University Hospitals NHS Foundation Trust, Blackshaw Road, London, SW17 0QT UK
| | - Sarah Trippier
- Stroke Clinical Research Network, St George’s University Hospitals NHS Foundation Trust, Blackshaw Road, London, SW17 0QT UK
| | - Shai Betteridge
- Department of Neuropsychology, St George’s University Hospitals NHS Foundation Trust, Blackshaw Road, London, SW17 0QT UK
| | - Franklyn A. Howe
- Neurosciences Research Centre, Molecular and Clinical Sciences Research Institute, St George’s University of London, Cranmer Terrace, London, SW17 0RE UK
| | - Usman Khan
- Department of Neurology, St George’s University Hospitals NHS Foundation Trust, Blackshaw Road, London, SW17 0QT UK
| | - Christina Kruuse
- Department of Neurology, Herlev Hospital, Herlev Ringvej 75, 2730 Herlev, Denmark
| | - Jeremy B. Madigan
- Neurosciences Research Centre, Molecular and Clinical Sciences Research Institute, St George’s University of London, Cranmer Terrace, London, SW17 0RE UK
- Department of Neuroradiology, St George’s University Hospitals NHS Foundation Trust, Blackshaw Road, London, SW17 0QT UK
| | | | - Anthony C. Pereira
- Department of Neurology, St George’s University Hospitals NHS Foundation Trust, Blackshaw Road, London, SW17 0QT UK
| | - Debbie Rolfe
- Joint Research and Enterprise Office, St George’s University of London, Cranmer Terrace, London, SW17 0RE UK
| | - Egill Rostrup
- Department of Clinical Physiology and Nuclear Medicine, Rigshospitalet, Nordre Ringvej 57, DK-2600 Glostrup, Denmark
| | - Caroline E. Haig
- Robertson Centre for Biostatistics, University of Glasgow, Glasgow, G12 8QQ UK
| | - Thomas R. Barrick
- Neurosciences Research Centre, Molecular and Clinical Sciences Research Institute, St George’s University of London, Cranmer Terrace, London, SW17 0RE UK
| | - Jeremy D. Isaacs
- Neurosciences Research Centre, Molecular and Clinical Sciences Research Institute, St George’s University of London, Cranmer Terrace, London, SW17 0RE UK
- Cell Biology and Genetics Research Centre, Molecular and Clinical Sciences Research Institute, St George’s University of London, Cranmer Terrace, London, SW17 0RE UK
- Department of Neurology, St George’s University Hospitals NHS Foundation Trust, Blackshaw Road, London, SW17 0QT UK
| | - Atticus H. Hainsworth
- Neurosciences Research Centre, Molecular and Clinical Sciences Research Institute, St George’s University of London, Cranmer Terrace, London, SW17 0RE UK
- Cell Biology and Genetics Research Centre, Molecular and Clinical Sciences Research Institute, St George’s University of London, Cranmer Terrace, London, SW17 0RE UK
- Department of Neurology, St George’s University Hospitals NHS Foundation Trust, Blackshaw Road, London, SW17 0QT UK
- Cerebrovascular Disease, St George’s University of London, Cranmer Terrace, London, SW17 0RE UK
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Abstract
Background There is increasing interest in how culture may affect the quality of healthcare services, and previous research has shown that ‘treatment culture’—of which there are three categories (resident centred, ambiguous and traditional)—in a nursing home may influence prescribing of psychoactive medications. Objective The objective of this study was to explore and understand treatment culture in prescribing of psychoactive medications for older people with dementia in nursing homes. Method Six nursing homes—two from each treatment culture category—participated in this study. Qualitative data were collected through semi-structured interviews with nursing home staff and general practitioners (GPs), which sought to determine participants’ views on prescribing and administration of psychoactive medication, and their understanding of treatment culture and its potential influence on prescribing of psychoactive drugs. Following verbatim transcription, the data were analysed and themes were identified, facilitated by NVivo® and discussion within the research team. Results Interviews took place with five managers, seven nurses, 13 care assistants and two GPs. Four themes emerged: the characteristics of the setting, the characteristics of the individual, relationships and decision making. The characteristics of the setting were exemplified by views of the setting, daily routines and staff training. The characteristics of the individual were demonstrated by views on the personhood of residents and staff attitudes. Relationships varied between staff within and outside the home. These relationships appeared to influence decision making about prescribing of medications. The data analysis found that each home exhibited traits that were indicative of its respective assigned treatment culture. Conclusion Nursing home treatment culture appeared to be influenced by four main themes. Modification of these factors may lead to a shift in culture towards a more flexible, resident-centred culture and a reduction in prescribing and use of psychoactive medication. Electronic supplementary material The online version of this article (doi:10.1007/s40801-016-0066-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Catherine Shaw
- School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, Northern Ireland, UK
| | - Brendan McCormack
- School of Health Sciences, Queen Margaret University, Musselburgh, Scotland, UK
| | - Carmel M Hughes
- School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, Northern Ireland, UK.
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