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"Dunn, Graham"
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Contact inhibition of locomotion in vivo controls neural crest directional migration
by
Moreno, Mauricio
,
Parsons, Maddy
,
Mayor, Roberto
in
Animals
,
Biological and medical sciences
,
Cell Communication
2008
Close cellular encounters: neural crest cells prove a point
The phenomenon of contact inhibition of cell movement (or locomotion) was first identified more than 50 years ago in fibroblast cells
in vitro
, and defective contact inhibition is suggested as a factor in malignant cell invasiveness. It occurs when two cells touch; they retract their protrusions and change their direction of movement. But the molecular basis of this inhibition, and whether it happens
in vivo
, are still matters of controversy. Now time-lapse microscopy of neural crest cells, highly migratory cells of embryonic origin, has been used to demonstrate contact inhibition of locomotion both
in vivo
and
in vitro
, and that it can account for their directional migration. But when a neural crest cell meets another cell type it fails to display contact inhibition of locomotion, allowing it to invade the tissue.
This paper studies a phenomenon called contact inhibition of locomotion, whereby fibroblast cells grown in cell culture retract their protrusions and change their direction on contact. It is shown that this occurs
in vivo
, and the molecular basis is revealed. Neural crest cells, highly migratory cells of embryonic origin, exhibit contact inhibition of locomotion both
in vivo
and
in vitro
, which accounts for their directional migration. However, when a neural crest cell meets another cell type, it fails to display contact inhibition of locomotion, allowing it to invade the tissue.
Contact inhibition of locomotion was discovered by Abercrombie more than 50 years ago and describes the behaviour of fibroblast cells confronting each other
in vitro
, where they retract their protrusions and change direction on contact
1
,
2
. Its failure was suggested to contribute to malignant invasion
3
,
4
,
5
,
6
. However, the molecular basis of contact inhibition of locomotion and whether it also occurs
in vivo
are still unknown. Here we show that neural crest cells, a highly migratory and multipotent embryonic cell population, whose behaviour has been likened to malignant invasion
6
,
7
,
8
, demonstrate contact inhibition of locomotion both
in vivo
and
in vitro
, and that this accounts for their directional migration. When two migrating neural crest cells meet, they stop, collapse their protrusions and change direction. In contrast, when a neural crest cell meets another cell type, it fails to display contact inhibition of locomotion; instead, it invades the other tissue, in the same manner as metastatic cancer cells
3
,
5
,
9
. We show that inhibition of non-canonical Wnt signalling abolishes both contact inhibition of locomotion and the directionality of neural crest migration. Wnt-signalling members localize at the site of cell contact, leading to activation of RhoA in this region. These results provide the first example of contact inhibition of locomotion
in vivo
, provide an explanation for coherent directional migration of groups of cells and establish a previously unknown role for non-canonical Wnt signalling.
Journal Article
Patient empowerment: The need to consider it as a measurable patient-reported outcome for chronic conditions
by
Dunn, Graham
,
McAllister, Marion
,
Todd, Chris
in
Care and treatment
,
Case studies
,
Chronic Disease - psychology
2012
Background
Health policy in the UK and elsewhere is prioritising patient empowerment and patient evaluations of healthcare. Patient reported outcome measures now take centre-stage in implementing strategies to increase patient empowerment. This article argues for consideration of patient empowerment itself as a directly measurable patient reported outcome for chronic conditions, highlights some issues in adopting this approach, and outlines a research agenda to enable healthcare evaluation on the basis of patient empowerment.
Discussion
Patient empowerment is not a well-defined construct. A range of condition-specific and generic patient empowerment questionnaires have been developed; each captures a different construct
e.g.
personal control, self-efficacy/self-mastery, and each is informed by a different implicit or explicit theoretical framework. This makes it currently problematic to conduct comparative evaluations of healthcare services on the basis of patient empowerment. A case study (clinical genetics) is used to (1) illustrate that patient empowerment can be a valued healthcare outcome, even if patients do not obtain health status benefits, (2) provide a rationale for conducting work necessary to tighten up the patient empowerment construct (3) provide an exemplar to inform design of interventions to increase patient empowerment in chronic disease. Such initiatives could be evaluated on the basis of measurable changes in patient empowerment, if the construct were properly operationalised as a patient reported outcome measure. To facilitate this, research is needed to develop an appropriate and widely applicable generic theoretical framework of patient empowerment to inform (re)development of a generic measure. This research should include developing consensus between patients, clinicians and policymakers about the content and boundaries of the construct before operationalisation. This article also considers a number of issues for society and for healthcare providers raised by adopting the patient empowerment paradigm.
Summary
Healthcare policy is driving the need to consider patient empowerment as a measurable patient outcome from healthcare services. Research is needed to (1) tighten up the construct (2) develop consensus about what is important to include (3) (re)develop a generic measure of patient empowerment for use in evaluating healthcare (4) understand if/how people make trade-offs between empowerment and gain in health status.
Journal Article
Evaluation of a Calibrated 18F-FDG PET Score as a Biomarker for Progression in Alzheimer Disease and Mild Cognitive Impairment
by
Dunn, Graham
,
Westwood, Sarah
,
Haense, Cathleen
in
Alzheimer's disease
,
biomarkers
,
Clinical trials
2011
Increasingly, clinical trials are being planned in patients with mild cognitive impairment (MCI) to prevent or delay the onset of dementia in Alzheimer disease (AD) by disease-modifying intervention. Inclusion of imaging techniques as biomarkers for patient selection and assessment of outcome is expected to increase trial efficacy. PET using 18F-FDG provides objective information about the impairment of synaptic function and could, with appropriate standardization, qualify as a biomarker. METHODS: We evaluated a predefined quantitative measure (PET score) that is extracted automatically from 18F-FDG PET scans using a sample of controls (n = 44), patients with MCI (n = 94), and patients with mild AD (n = 40) from the Alzheimer Disease Neuroimaging Initiative (ADNI). Subjects received 4 scans and clinical assessments over 2 y. RESULTS: PET scores provide much higher test-retest reliability than standard neuropsychologic test scores (Alzheimer's Disease Assessment Scale-Cognitive [ADAS-cog] and Mini-Mental State Examination) and superior signal strength for measuring progression. At the same time, they are related linearly to ADAS-cog scores, thus providing a valid measure of cognitive impairment. In addition, PET scores at study entry in MCI patients significantly predict clinical progression to dementia with a higher accuracy than Mini-Mental State Examination and ADAS-cog. CONCLUSION: 18F-FDG PET scores are a valid imaging biomarker to monitor the progression of MCI to AD. Their superior test-retest reliability and signal strength will allow the reduction in the number of subjects needed or shortening of study duration substantially.
Journal Article
Cognitive therapy for people with schizophrenia spectrum disorders not taking antipsychotic drugs: a single-blind randomised controlled trial
by
Dunn, Graham
,
Callcott, Pauline
,
Cummings, Anna
in
Adult and adolescent clinical studies
,
Antipsychotic Agents
,
Behavior therapy. Cognitive therapy
2014
Antipsychotic drugs are usually the first line of treatment for schizophrenia; however, many patients refuse or discontinue their pharmacological treatment. We aimed to establish whether cognitive therapy was effective in reducing psychiatric symptoms in people with schizophrenia spectrum disorders who had chosen not to take antipsychotic drugs.
We did a single-blind randomised controlled trial at two UK centres between Feb 15, 2010, and May 30, 2013. Participants aged 16–65 years with schizophrenia spectrum disorders, who had chosen not to take antipsychotic drugs for psychosis, were randomly assigned (1:1), by a computerised system with permuted block sizes of four or six, to receive cognitive therapy plus treatment as usual, or treatment as usual alone. Randomisation was stratified by study site. Outcome assessors were masked to group allocation. Our primary outcome was total score on the positive and negative syndrome scale (PANSS), which we assessed at baseline, and at months 3, 6, 9, 12, 15, and 18. Analysis was by intention to treat, with an ANCOVA model adjusted for site, age, sex, and baseline symptoms. This study is registered as an International Standard Randomised Controlled Trial, number 29607432.
74 individuals were randomly assigned to receive either cognitive therapy plus treatment as usual (n=37), or treatment as usual alone (n=37). Mean PANSS total scores were consistently lower in the cognitive therapy group than in the treatment as usual group, with an estimated between-group effect size of −6·52 (95% CI −10·79 to −2·25; p=0·003). We recorded eight serious adverse events: two in patients in the cognitive therapy group (one attempted overdose and one patient presenting risk to others, both after therapy), and six in those in the treatment as usual group (two deaths, both of which were deemed unrelated to trial participation or mental health; three compulsory admissions to hospital for treatment under the mental health act; and one attempted overdose).
Cognitive therapy significantly reduced psychiatric symptoms and seems to be a safe and acceptable alternative for people with schizophrenia spectrum disorders who have chosen not to take antipsychotic drugs. Evidence-based treatments should be available to these individuals. A larger, definitive trial is needed.
National Institute for Health Research.
Journal Article
Clinical outcomes of Joint Crisis Plans to reduce compulsory treatment for people with psychosis: a randomised controlled trial
2013
The CRIMSON (CRisis plan IMpact: Subjective and Objective coercion and eNgagement) study is an individual level, randomised controlled trial that compared the effectiveness of Joint Crisis Plans (JCPs) with treatment as usual for people with severe mental illness. The JCP is a negotiated statement by a patient of treatment preferences for any future psychiatric emergency, when he or she might be unable to express clear views. We assessed whether the additional use of JCPs improved patient outcomes compared with treatment as usual.
Patients were eligible if they had at least one psychiatric admission in the previous 2 years and were on the Enhanced Care Programme Approach register. The study was done with 64 generic and specialist community mental health teams in four English mental health care provider organisations (trusts). Hypotheses tested were that, compared with the control group, the intervention group would experience: fewer compulsory admissions (primary outcome); fewer psychiatric admissions; shorter psychiatric stays; lower perceived coercion; improved therapeutic relationships; and improved engagement. We stratified participants by centre. The research team but not participants nor clinical staff were masked to allocation. This study is registered with ClinicalTrials.gov, number ISRCTN11501328.
569 participants were randomly assigned (285 to the intervention group and 284 to the control group). No significant treatment effect was seen for the primary outcome (56 [20%] sectioned in the control group and 49 [18%] in the JCP group; odds ratio 0·90 [95% CI 0·58–1·39, p=0·63]) or any secondary outcomes, with the exception of an improved secondary outcome of therapeutic relationships (17·3 [7·6] vs 16·0 [7·1]; adjusted difference −1·28 [95% CI −2·56 to −0·01, p=0·049]). Qualitative data supported this finding.
Our findings are inconsistent with two earlier JCP studies, and show that the JCP is not significantly more effective than treatment as usual. There is evidence to suggest the JCPs were not fully implemented in all study sites, and were combined with routine clinical review meetings which did not actively incorporate patients' preferences. The study therefore raises important questions about implementing new interventions in routine clinical practice.
Medical Research Council UK and the National Institute for Health Research.
Journal Article
The impact of moderator by confounder interactions in the assessment of treatment effect modification: a simulation study
by
Dunn, Graham
,
Marsden, Antonia Mary
,
Dixon, William G.
in
Bias
,
Computer Simulation
,
Confounding
2022
Background
When performed in an observational setting, treatment effect modification analyses should account for all confounding, where possible. Often, such studies only consider confounding between the exposure and outcome. However, there is scope for misspecification of the confounding adjustment when estimating moderation as the effects of the confounders may themselves be influenced by the moderator. The aim of this study was to investigate bias in estimates of treatment effect modification resulting from failure to account for an interaction between a binary moderator and a confounder on either treatment receipt or the outcome, and to assess the performance of different approaches to account for such interactions.
Methods
The theory behind the reason for bias and factors that impact the magnitude of bias is explained. Monte Carlo simulations were used to assess the performance of different propensity scores adjustment methods and regression adjustment where the adjustment 1) did not account for any moderator-confounder interactions, 2) included moderator-confounder interactions, and 3) was estimated separately in each moderator subgroup. A real-world observational dataset was used to demonstrate this issue.
Results
Regression adjustment and propensity score covariate adjustment were sensitive to the presence of moderator-confounder interactions on outcome, whilst propensity score weighting and matching were more sensitive to the presence of moderator-confounder interactions on treatment receipt. Including the relevant moderator-confounder interactions in the propensity score (for methods using this) or the outcome model (for regression adjustment) rectified this for all methods except propensity score covariate adjustment. For the latter, subgroup-specific propensity scores were required. Analysis of the real-world dataset showed that accounting for a moderator-confounder interaction can change the estimate of effect modification.
Conclusions
When estimating treatment effect modification whilst adjusting for confounders, moderator-confounder interactions on outcome or treatment receipt should be accounted for.
Journal Article
Arp2/3 complex interactions and actin network turnover in lamellipodia
by
Szczodrak, Malgorzata
,
Mannherz, Hans G
,
Stradal, Theresia EB
in
Actin Capping Proteins - metabolism
,
Actin Depolymerizing Factors - metabolism
,
Actin-Related Protein 2-3 Complex - metabolism
2008
Cell migration is initiated by lamellipodia—membrane‐enclosed sheets of cytoplasm containing densely packed actin filament networks. Although the molecular details of network turnover remain obscure, recent work points towards key roles in filament nucleation for Arp2/3 complex and its activator WAVE complex. Here, we combine fluorescence recovery after photobleaching (FRAP) of different lamellipodial components with a new method of data analysis to shed light on the dynamics of actin assembly/disassembly. We show that Arp2/3 complex is incorporated into the network exclusively at the lamellipodium tip, like actin, at sites coincident with WAVE complex accumulation. Capping protein likewise showed a turnover similar to actin and Arp2/3 complex, but was confined to the tip. In contrast, cortactin—another prominent Arp2/3 complex regulator—and ADF/cofilin—previously implicated in driving both filament nucleation and disassembly—were rapidly exchanged throughout the lamellipodium. These results suggest that Arp2/3‐ and WAVE complex‐driven actin filament nucleation at the lamellipodium tip is uncoupled from the activities of both cortactin and cofilin. Network turnover is additionally regulated by the spatially segregated activities of capping protein at the tip and cofilin throughout the mesh.
Journal Article
Measuring Metacognition in Cancer: Validation of the Metacognitions Questionnaire 30 (MCQ-30)
2014
The Metacognitions Questionnaire 30 assesses metacognitive beliefs and processes which are central to the metacognitive model of emotional disorder. As recent studies have begun to explore the utility of this model for understanding emotional distress after cancer diagnosis, it is important also to assess the validity of the Metacognitions Questionnaire 30 for use in cancer populations.
229 patients with primary breast or prostate cancer completed the Metacognitions Questionnaire 30 and the Hospital Anxiety and Depression Scale pre-treatment and again 12 months later. The structure and validity of the Metacognitions Questionnaire 30 were assessed using factor analyses and structural equation modelling.
Confirmatory and exploratory factor analyses provided evidence supporting the validity of the previously published 5-factor structure of the Metacognitions Questionnaire 30. Specifically, both pre-treatment and 12 months later, this solution provided the best fit to the data and all items loaded on their expected factors. Structural equation modelling indicated that two dimensions of metacognition (positive and negative beliefs about worry) were significantly associated with anxiety and depression as predicted, providing further evidence of validity.
These findings provide initial evidence that the Metacognitions Questionnaire 30 is a valid measure for use in cancer populations.
Journal Article
Automated psychological therapy using virtual reality (VR) for patients with persecutory delusions: study protocol for a single-blind parallel-group randomised controlled trial (THRIVE)
by
Dunn, Graham
,
Clark, David
,
Waite, Felicity
in
Antipsychotics
,
Automated delivery
,
Automation
2019
Background
Persecutory delusions are a major psychiatric problem and are associated with a wide range of adverse outcomes. Our theoretical model views these delusions as unfounded threat beliefs which persist due to defence behaviours (e.g. avoidance) that prevent disconfirmatory evidence being processed. The treatment implications are that patients need to (1) go into feared situations and (2) not use defence behaviours. This enables relearning of safety and hence paranoia diminution. However, this is very difficult for patients due to their severe anxiety. A solution is to use virtual reality (VR) social situations, which are graded in difficulty and which patients find much easier to enter. We have now automated the provision of cognitive therapy within VR using an avatar coach, so that a therapist is not required and the treatment is scalable. In the THRIVE trial, the automated VR cognitive treatment will be tested against a VR control condition. It will contribute to our wider programme of work developing VR for patients with psychosis.
Methods
Patients with persistent persecutory delusions in the context of non-affective psychosis will be randomised (1:1) to the automated VR cognitive treatment or VR mental relaxation (control condition). Each VR treatment will comprise approximately four sessions of 30 min. Standard care will remain as usual in both groups. Assessments will be carried out at 0, 2, 4 (post treatment), 8, 16, and 24 weeks by a researcher blind to treatment allocation. The primary outcome is degree of conviction in the persecutory delusion (primary endpoint 4 weeks). Effect sizes will be re-established by an interim analysis of 30 patients. If the interim effect size suggests that the treatment is worth pursuing (
d
> 0.1), then the trial will go on to test 90 patients in total. Secondary outcomes include real world distress, activity levels, suicidal ideation, and quality of life. Mediation will also be tested. All main analyses will follow the intention-to-treat principle. The trial is funded by the Medical Research Council Developmental Pathway Funding Scheme.
Discussion
The trial will provide the first test of automated cognitive therapy within VR for patients with psychosis. The treatment is potentially highly scalable for treatment services.
Trial registration
ISRCTN,
ISRCTN12497310
. Registered on 14 August 2018.
Journal Article
The feasibility and validity of ambulatory self-report of psychotic symptoms using a smartphone software application
2012
Background
Semi-structured interview scales for psychosis are the gold standard approach to assessing psychotic and other symptoms. However, such assessments have limitations such as recall bias, averaging, insensitivity to change and variable interrater reliability. Ambulant, real-time self-report assessment devices may hold advantages over interview measures, but it needs to be shown that the data thus collected are valid, and the collection method is acceptable, feasible and safe. We report on a monitoring system for the assessment of psychosis using smartphone technology. The primary aims were to: i) assess validity through correlations of item responses with those on widely accepted interview assessments of psychosis, and ii) examine compliance to the procedure in individuals with psychosis of varying severity.
Methods
A total of 44 participants (acute or remitted DSM-4 schizophrenia and related disorders, and prodromal) completed 14 branching self-report items concerning key psychotic symptoms on a touch-screen mobile phone when prompted by an alarm at six pseudo-random times, each day, for one week. Face to face PANSS and CDS interviews were conducted before and after the assessment period blind to the ambulant data.
Results
Compliance as defined by completion of at least 33% of all possible data-points over seven days was 82%. In the 36 compliant participants, 5 items (delusions, hallucinations, suspiciousness, anxiety, hopelessness) showed moderate to strong (
rho
0.6-0.8) associations with corresponding items from interview rating scales. Four items showed no significant correlation with rating scales: each was an item based on observable behaviour. Ambulant ratings showed excellent test-retest reliability and sensitivity to change.
Conclusions
Ambulatory monitoring of symptoms several times daily using smartphone software applications represents a feasible and valid way of assessing psychotic phenomena for research and clinical management purposes. Further evaluation required over longer assessment periods, in clinical trials and service settings.
Journal Article