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result(s) for
"Allan, Alasdair J."
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The parenting hub of the hypothalamus is a focus of imprinted gene action
by
John, Rosalind M.
,
Higgs, Matthew J.
,
Allan, Alasdair J.
in
Analysis
,
Animals
,
Antigens, Neoplasm - genetics
2023
Imprinted genes are subject to germline epigenetic modification resulting in parental-specific allelic silencing. Although genomic imprinting is thought to be important for maternal behaviour, this idea is based on serendipitous findings from a small number of imprinted genes. Here, we undertook an unbiased systems biology approach, taking advantage of the recent delineation of specific neuronal populations responsible for controlling parental care, to test whether imprinted genes significantly converge to regulate parenting behaviour. Using single-cell RNA sequencing datasets, we identified a specific enrichment of imprinted gene expression in a recognised “parenting hub”, the galanin-expressing neurons of the preoptic area. We tested the validity of linking enriched expression in these neurons to function by focusing on MAGE family member L2 (Magel2) , an imprinted gene not previously linked to parenting behaviour. We confirmed expression of Magel2 in the preoptic area galanin expressing neurons. We then examined the parenting behaviour of Magel2 -null (+/p) mice. Magel 2-null mothers, fathers and virgin females demonstrated deficits in pup retrieval, nest building and pup-directed motivation, identifying a central role for this gene in parenting. Finally, we show that Magel2- null mothers and fathers have a significant reduction in POA galanin expressing cells, which in turn contributes to a reduced c-Fos response in the POA upon exposure to pups. Our findings identify a novel imprinted gene that impacts parenting behaviour and, moreover, demonstrates the utility of using single-cell RNA sequencing data to predict gene function from expression and in doing so here, have identified a purposeful role for genomic imprinting in mediating parental behaviour.
Journal Article
Long-read sequencing for fast and robust identification of correct genome-edited alleles: PCR-based and Cas9 capture methods
by
Mackenzie, Matthew
,
Malzer, Elke
,
McCabe, Christopher V.
in
Accuracy
,
Alleles
,
Allelomorphism
2024
Recent developments in CRISPR/Cas9 genome-editing tools have facilitated the introduction of precise alleles, including genetic intervals spanning several kilobases, directly into the embryo. However, the introduction of donor templates, via homology directed repair, can be erroneous or incomplete and these techniques often produce mosaic founder animals. Thus, newly generated alleles must be verified at the sequence level across the targeted locus. Screening for the presence of the desired mutant allele using traditional sequencing methods can be challenging due to the size of the interval to be sequenced, together with the mosaic nature of founders.
In order to help disentangle the genetic complexity of these animals, we tested the application of Oxford Nanopore Technologies long-read sequencing at the targeted locus and found that the achievable depth of sequencing is sufficient to offset the sequencing error rate associated with the technology used to validate targeted regions of interest. We have assembled an analysis workflow that facilitates interrogating the entire length of a targeted segment in a single read, to confirm that the intended mutant sequence is present in both heterozygous animals and mosaic founders. We used this workflow to compare the output of PCR-based and Cas9 capture-based targeted sequencing for validation of edited alleles.
Targeted long-read sequencing supports in-depth characterisation of all experimental models that aim to produce knock-in or conditional alleles, including those that contain a mix of genome-edited alleles. PCR- or Cas9 capture-based modalities bring different advantages to the analysis.
Journal Article
Application of long single-stranded DNA donors in genome editing: generation and validation of mouse mutants
by
Mackenzie, Matthew
,
McCabe, Christopher V.
,
Stewart, Michelle E.
in
Allele validation
,
Alleles
,
Animal models
2018
Background
Recent advances in clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) genome editing have led to the use of long single-stranded DNA (lssDNA) molecules for generating conditional mutations. However, there is still limited available data on the efficiency and reliability of this method.
Results
We generated conditional mouse alleles using lssDNA donor templates and performed extensive characterization of the resulting mutations. We observed that the use of lssDNA molecules as donors efficiently yielded founders bearing the conditional allele, with seven out of nine projects giving rise to modified alleles. However, rearranged alleles including nucleotide changes, indels, local rearrangements and additional integrations were also frequently generated by this method. Specifically, we found that alleles containing unexpected point mutations were found in three of the nine projects analyzed. Alleles originating from illegitimate repairs or partial integration of the donor were detected in eight projects. Furthermore, additional integrations of donor molecules were identified in four out of the seven projects analyzed by copy counting. This highlighted the requirement for a thorough allele validation by polymerase chain reaction, sequencing and copy counting of the mice generated through this method. We also demonstrated the feasibility of using lssDNA donors to generate thus far problematic point mutations distant from active CRISPR cutting sites by targeting two distinct genes (
Gckr
and
Rims1
). We propose a strategy to perform extensive quality control and validation of both types of mouse models generated using lssDNA donors.
Conclusion
lssDNA donors reproducibly generate conditional alleles and can be used to introduce point mutations away from CRISPR/Cas9 cutting sites in mice. However, our work demonstrates that thorough quality control of new models is essential prior to reliably experimenting with mice generated by this method. These advances in genome editing techniques shift the challenge of mutagenesis from generation to the validation of new mutant models.
Journal Article
Application of long-read sequencing for robust identification of correct alleles in genome edited animals
2019
Recent developments in CRISPR/Cas9 genome editing tools have facilitated the introduction of more complex alleles, often spanning genetic intervals of several kilobases, directly into the embryo. These techniques often produce mosaic founder animals and the introduction of donor templates, via homologous directed repair, can be erroneous or incomplete. Newly generated alleles must be verified at the sequence level across the targeted locus. Screening for the presence of the desired mutant allele using traditional sequencing methods can be challenging due to the size of the desired edit(s) together with founder mosaicism. In order to help disentangle the genetic complexity of these animals, we tested the application of Oxford Nanopore long read sequencing of the targeted locus. Taking advantage of sequencing the entire length of the segment in each single read, we were able to determine whether the entire intended mutant sequence was present in both mosaic founders and their offspring. Footnotes * https://www.ebi.ac.uk/ena * https://gitlab.com/nick297/cas9point4
New founs fae auld larachs: leid-plannin for scots
by
Allan, Alasdair J
in
Linguistics
1998
After introducing the concepts of language maintenance and language-planning, the thesis outlines the current status of a selection of European minority languages. These are later drawn upon in order to make comparisons about the present state of Scots and possible ways forward for its language activists.The language's identity crisis and consequent problems for language maintenance are examined, and the conclusion reached that major intervention in both status and corpus planning is required for the language to have any secure future. Potential areas for status planning are discussed, focusing on the options for the short and medium terms.The latter part of the thesis concentrates on the problems for corpus-planners, discussing the alternatives for solutions in the fields of orthography, lexicon and grammar.The greatest problem for Scots is the depth of public and official ignorance surrounding it. The author's argument is that will only change when Scots' own advocates understand that the case for language maintenance is more than a case for Scots poetry. Rather, it implies an extensive campaign for status-planning measures, most of which have implications in the field of corpus planning.The thesis is written in Scots.
Dissertation
Delirium detection in older acute medical inpatients: a multicentre prospective comparative diagnostic test accuracy study of the 4AT and the confusion assessment method
by
Goodacre, Steve
,
Stephen, Jacqueline
,
Weir, Christopher J.
in
Acute Disease
,
Aged
,
Aged, 80 and over
2019
Background
Delirium affects > 15% of hospitalised patients but is grossly underdetected, contributing to poor care. The 4 ‘A’s Test (4AT,
www.the4AT.com
) is a short delirium assessment tool designed for routine use without special training. The primary objective was to assess the accuracy of the 4AT for delirium detection. The secondary objective was to compare the 4AT with another commonly used delirium assessment tool, the Confusion Assessment Method (CAM).
Methods
This was a prospective diagnostic test accuracy study set in emergency departments or acute medical wards involving acute medical patients aged ≥ 70. All those without acutely life-threatening illness or coma were eligible. Patients underwent (1) reference standard delirium assessment based on DSM-IV criteria and (2) were randomised to either the index test (4AT, scores 0–12; prespecified score of > 3 considered positive) or the comparator (CAM; scored positive or negative), in a random order, using computer-generated pseudo-random numbers, stratified by study site, with block allocation. Reference standard and 4AT or CAM assessments were performed by pairs of independent raters blinded to the results of the other assessment.
Results
Eight hundred forty-three individuals were randomised: 21 withdrew, 3 lost contact, 32 indeterminate diagnosis, 2 missing outcome, and 785 were included in the analysis. Mean age was 81.4 (SD 6.4) years. 12.1% (95/785) had delirium by reference standard assessment, 14.3% (56/392) by 4AT, and 4.7% (18/384) by CAM. The 4AT had an area under the receiver operating characteristic curve of 0.90 (95% CI 0.84–0.96). The 4AT had a sensitivity of 76% (95% CI 61–87%) and a specificity of 94% (95% CI 92–97%). The CAM had a sensitivity of 40% (95% CI 26–57%) and a specificity of 100% (95% CI 98–100%).
Conclusions
The 4AT is a short, pragmatic tool which can help improving detection rates of delirium in routine clinical care.
Trial registration
International standard randomised controlled trial number (ISRCTN)
53388093
. Date applied 30/05/2014; date assigned 02/06/2014.
Journal Article
The design and development of a home-based rehabilitation programme for those recovering after an episode of delirium
by
Litherland, Rachael
,
Goodwin, Elizabeth
,
Allan, Louise
in
Care and treatment
,
Complex intervention
,
Delirium
2025
Background
Delirium, closely linked to increasing age and frailty, is a growing concern in the aging population, yet there is little understanding about how to support recovery for individuals and their carers. This paper details the design and development of RecoverED, a home-based rehabilitation intervention for delirium recovery.
Methods
A realist-informed approach was used to develop a programme theory and logic model for RecoverED. A rapid realist review had identified strategies for delirium recovery, followed by interviews with stakeholders (older adults, carers, and professionals), and an expert panel discussion. The intervention was then developed based on the refined programme theory of what had worked to improve recovery from delirium, for whom, and in what context.
Results
The RecoverED intervention, described using the TIDieR checklist, was a complex, multicomponent, 12 week home-based programme delivered by a multidisciplinary team in up to 10 sessions. The intervention comprised cognitive, physical, and psychosocial components. An intervention manual and training programme had been developed to support delivery teams.
Conclusion
The RecoverED intervention was being evaluated in a multi-centre feasibility trial with a qualitative process evaluation. This paper describes theory-based rehabilitation interventions for long-term delirium recovery. Further research through a randomised controlled trial is needed to assess its effectiveness and cost-effectiveness before broader implementation.
Journal Article
Validation of a Consensus Method for Identifying Delirium from Hospital Records
2014
Delirium is increasingly considered to be an important determinant of trajectories of cognitive decline. Therefore, analyses of existing cohort studies measuring cognitive outcomes could benefit from methods to ascertain a retrospective delirium diagnosis. This study aimed to develop and validate such a method for delirium detection using routine medical records in UK and Ireland.
A point prevalence study of delirium provided the reference-standard ratings for delirium diagnosis. Blinded to study results, clinical vignettes were compiled from participants' medical records in a standardised manner, describing any relevant delirium symptoms recorded in the whole case record for the period leading up to case-ascertainment. An expert panel rated each vignette as unlikely, possible, or probable delirium and disagreements were resolved by consensus.
From 95 case records, 424 vignettes were abstracted by 5 trained clinicians. There were 29 delirium cases according to the reference standard. Median age of subjects was 76.6 years (interquartile range 54.6 to 82.5). Against the original study DSM-IV diagnosis, the chart abstraction method gave a positive likelihood ratio (LR) of 7.8 (95% CI 5.7-12.0) and the negative LR of 0.45 (95% CI 0.40-0.47) for probable delirium (sensitivity 0.58 (95% CI 0.53-0.62); specificity 0.93 (95% CI 0.90-0.95); AUC 0.86 (95% CI 0.82-0.89)). The method diagnosed possible delirium with positive LR 3.5 (95% CI 2.9-4.3) and negative LR 0.15 (95% CI 0.11-0.21) (sensitivity 0.89 (95% CI 0.85-0.91); specificity 0.75 (95% CI 0.71-0.79); AUC 0.86 (95% CI 0.80-0.89)).
This chart abstraction method can retrospectively diagnose delirium in hospitalised patients with good accuracy. This has potential for retrospectively identifying delirium in cohort studies where routine medical records are available. This example of record linkage between hospitalisations and epidemiological data may lead to further insights into the inter-relationship between acute illness, as an exposure, for a range of chronic health outcomes.
Journal Article
Population genomics of Escherichia coli in livestock-keeping households across a rapidly developing urban landscape
2022
Quantitative evidence for the risk of zoonoses and the spread of antimicrobial resistance remains lacking. Here, as part of the UrbanZoo project, we sampled
Escherichia coli
from humans, livestock and peri-domestic wildlife in 99 households across Nairobi, Kenya, to investigate its distribution among host species in this rapidly developing urban landscape. We performed whole-genome sequencing of 1,338
E. coli
isolates and found that the diversity and sharing patterns of
E. coli
were heavily structured by household and strongly shaped by host type. We also found evidence for inter-household and inter-host sharing and, importantly, between humans and animals, although this occurs much less frequently. Resistome similarity was differently distributed across host and household, consistent with being driven by shared exposure to antimicrobials. Our results indicate that a large, epidemiologically structured sampling framework combined with WGS is needed to uncover strain-sharing events among different host populations in complex environments and the major contributing pathways that could ultimately drive the emergence of zoonoses and the spread of antimicrobial resistance.
Phylogeography and phylogenomic analyses of
E. coli
isolates collected from humans and domesticated and wild animals across 99 households in Nairobi reveal strong intra-household, and lower but detectable inter-household and inter-host, strain-sharing patterns.
Journal Article
High-sensitivity troponin in the evaluation of patients with suspected acute coronary syndrome: a stepped-wedge, cluster-randomised controlled trial
by
Hung, John
,
Young, Stephen
,
Keerie, Catriona
in
Acute Coronary Syndrome - blood
,
Acute Coronary Syndrome - diagnosis
,
Acute coronary syndromes
2018
High-sensitivity cardiac troponin assays permit use of lower thresholds for the diagnosis of myocardial infarction, but whether this improves clinical outcomes is unknown. We aimed to determine whether the introduction of a high-sensitivity cardiac troponin I (hs-cTnI) assay with a sex-specific 99th centile diagnostic threshold would reduce subsequent myocardial infarction or cardiovascular death in patients with suspected acute coronary syndrome.
In this stepped-wedge, cluster-randomised controlled trial across ten secondary or tertiary care hospitals in Scotland, we evaluated the implementation of an hs-cTnI assay in consecutive patients who had been admitted to the hospitals' emergency departments with suspected acute coronary syndrome. Patients were eligible for inclusion if they presented with suspected acute coronary syndrome and had paired cardiac troponin measurements from the standard care and trial assays. During a validation phase of 6–12 months, results from the hs-cTnI assay were concealed from the attending clinician, and a contemporary cardiac troponin I (cTnI) assay was used to guide care. Hospitals were randomly allocated to early (n=5 hospitals) or late (n=5 hospitals) implementation, in which the high-sensitivity assay and sex-specific 99th centile diagnostic threshold was introduced immediately after the 6-month validation phase or was deferred for a further 6 months. Patients reclassified by the high-sensitivity assay were defined as those with an increased hs-cTnI concentration in whom cTnI concentrations were below the diagnostic threshold on the contemporary assay. The primary outcome was subsequent myocardial infarction or death from cardiovascular causes at 1 year after initial presentation. Outcomes were compared in patients reclassified by the high-sensitivity assay before and after its implementation by use of an adjusted generalised linear mixed model. This trial is registered with ClinicalTrials.gov, number NCT01852123.
Between June 10, 2013, and March 3, 2016, we enrolled 48 282 consecutive patients (61 [SD 17] years, 47% women) of whom 10 360 (21%) patients had cTnI concentrations greater than those of the 99th centile of the normal range of values, who were identified by the contemporary assay or the high-sensitivity assay. The high-sensitivity assay reclassified 1771 (17%) of 10 360 patients with myocardial injury or infarction who were not identified by the contemporary assay. In those reclassified, subsequent myocardial infarction or cardiovascular death within 1 year occurred in 105 (15%) of 720 patients in the validation phase and 131 (12%) of 1051 patients in the implementation phase (adjusted odds ratio for implementation vs validation phase 1·10, 95% CI 0·75 to 1·61; p=0·620).
Use of a high-sensitivity assay prompted reclassification of 1771 (17%) of 10 360 patients with myocardial injury or infarction, but was not associated with a lower subsequent incidence of myocardial infarction or cardiovascular death at 1 year. Our findings question whether the diagnostic threshold for myocardial infarction should be based on the 99th centile derived from a normal reference population.
The British Heart Foundation.
Journal Article