| 1. |
- Meyer, Esther, et al.
(author)
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Mutations in the histone methyltransferase gene KMT2B cause complex early-onset dystonia.
- 2017
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In: Nature genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 49, s. 223-237
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Journal article (peer-reviewed)abstract
- Histone lysine methylation, mediated by mixed-lineage leukemia (MLL) proteins, is now known to be critical in the regulation of gene expression, genomic stability, cell cycle and nuclear architecture. Despite MLL proteins being postulated as essential for normal development, little is known about the specific functions of the different MLL lysine methyltransferases. Here we report heterozygous variants in the gene KMT2B (also known as MLL4) in 27 unrelated individuals with a complex progressive childhood-onset dystonia, often associated with a typical facial appearance and characteristic brain magnetic resonance imaging findings. Over time, the majority of affected individuals developed prominent cervical, cranial and laryngeal dystonia. Marked clinical benefit, including the restoration of independent ambulation in some cases, was observed following deep brain stimulation (DBS). These findings highlight a clinically recognizable and potentially treatable form of genetic dystonia, demonstrating the crucial role of KMT2B in the physiological control of voluntary movement.
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| 2. |
- Beal, Jacob, et al.
(author)
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Robust estimation of bacterial cell count from optical density
- 2020
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In: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Journal article (peer-reviewed)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 3. |
- Carney, Daniel P. J., et al.
(author)
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Using developmental trajectories to examine verbal and visuospatial short-term memory development in children and adolescents with Williams and Down syndromes
- 2013
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In: Research in Developmental Disabilities. - : Elsevier. - 0891-4222 .- 1873-3379. ; 34:10, s. 3421-3432
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Journal article (peer-reviewed)abstract
- Williams (WS) and Down (DS) syndromes have been associated with specifically compromised short-term memory (STM) subsystems. Individuals with WS have shown impairments in visuospatial STM, while individuals with DS have often shown problems with the recall of verbal material. However, studies have not usually compared the development of STM skills in these domains, in these populations. The present study employed a cross-sectional developmental trajectories approach, plotting verbal and visuospatial STM performance against more general cognitive and chronological development, to investigate how the domain-specific skills of individuals with WS and DS may change as development progresses, as well as whether the difference between STM skill domains increases, in either group, as development progresses. Typically developing children, of broadly similar cognitive ability to the clinical groups, were also included. Planned between- and within-group comparisons were carried out. Individuals with WS and DS both showed the domain-specific STM weaknesses in overall performance that were expected based on the respective cognitive profiles. However, skills in both groups developed, according to general cognitive development, at similar rates to those of the TD group. In addition, no significant developmental divergence between STM domains was observed in either clinical group according to mental age or chronological age, although the general pattern of findings indicated that the influence of the latter variable across STM domains, particularly in WS, might merit further investigation.
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| 4. |
- Henry, Lucy A., et al.
(author)
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Hebb repetition learning in adolescents with intellectual disabilities
- 2022
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In: Research in Developmental Disabilities. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0891-4222 .- 1873-3379. ; 125
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Journal article (peer-reviewed)abstract
- BackgroundHebb repetition learning is a form of long-term serial order learning that can occur when sequences of items in an immediate serial recall task are repeated. Repetition improves performance because of the gradual integration of serial order information from short-term memory into a more stable long-term memory trace.AimsThe current study assessed whether adolescents with non-specific intellectual disabilities showed Hebb repetition effects, and if their magnitude was equivalent to those of children with typical development, matched for mental age.MethodsTwo immediate serial recall Hebb repetition learning tasks using verbal and visuospatial materials were presented to 47 adolescents with intellectual disabilities (11–15 years) and 47 individually mental age-matched children with typical development (4–10 years).ResultsBoth groups showed Hebb repetition learning effects of similar magnitude, albeit with some reservations. Evidence for Hebb repetition learning was found for both verbal and visuospatial materials; for our measure of Hebb learning the effects were larger for verbal than visuospatial materials.ConclusionsThe findings suggested that adolescents with intellectual disabilities may show implicit long-term serial-order learning broadly commensurate with mental age level. The benefits of using repetition in educational contexts for adolescents with intellectual disabilities are considered.
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| 5. |
- Henry, Lucy A., et al.
(author)
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The reliability of Hebb repetition learning and its association with language and reading in adolescents with intellectual disabilities
- 2024
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In: Cortex. - : ELSEVIER MASSON, CORP OFF. - 0010-9452 .- 1973-8102. ; 177, s. 253-267
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Journal article (peer-reviewed)abstract
- Hebb repetition learning (HRL) refers to neurodevelopmental processes characterised by repeated stimulus exposure without feedback, which result in changes in behaviour and/or responses, e.g., long-term learning of serial order. Here, we investigate effects of HRL on serial order memory. The present research aimed to assess the reliability of new HRL measures and investigate their relationships with language and reading skills (vocabulary, grammar, word reading) in adolescents with intellectual disability (ID). A comparison group of children of similar mental age with typical development (TD) was also assessed. ID and TD groups were tested on HRL tasks, evaluating test-retest and split-half reliability. The relationship between HRL and language and reading was analysed after accounting for the influence of mental age and verbal short-term memory. The HRL tasks displayed moderate test-retest (and split-half) reliability, HRL tasks with different stimuli (verbal, visual) were related, and we identified issues with one method of HRL scoring. The planned regression analyses failed to show relationships between HRL and language/reading skills in both groups when mental age, a very strong predictor, was included. However, further exploratory regression analyses without mental age revealed HRL's predictive capabilities for vocabulary in the ID group and reading in the TD group, results which need further investigation and replication. HRL displays promise as a moderately reliable metric and exhibits varied and interpretable predictive capabilities for language and reading skills across groups. (c) 2024 The Authors. Published by Elsevier Ltd. This is an open access article under the CC
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| 6. |
- Messer, David, et al.
(author)
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The Perfect Match! A Review and Tutorial on Issues Related to Matching Groups in Investigations of Children with Neurodevelopmental Conditions
- 2023
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In: Brain Sciences. - : MDPI. - 2076-3425. ; 13:10
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Research review (peer-reviewed)abstract
- Research concerned with children and young people who have neurodevelopmental disabilities (ND) in relation to early language acquisition usually involves comparisons with matched group(s) of typically developing individuals. In these studies, several important and complex issues need to be addressed. Three major issues are related to: (1) the choice of a variables on which to carry out group matching; (2) recruiting children into the study; and (3) the statistical analysis of the data. To assist future research on this topic, we discuss each of these three issues and provide recommendations about what we believe to be the best course of action. To provide a comprehensive review of the methodological issues, we draw on research beyond the topic of early language acquisition. Our overall aim is to contribute to research that considers questions about delay or differences in development patterns of development and about identifying potentially causal variables.
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| 7. |
- Poloczek, Sebastian, et al.
(author)
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Strategic verbal rehearsal in adolescents with mild intellectual disabilities: A multi-centre European study
- 2016
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In: Research in Developmental Disabilities. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0891-4222 .- 1873-3379. ; 58, s. 83-93
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Journal article (peer-reviewed)abstract
- Background: There is a long-held view that verbal short-term memory problems of individuals with intellectual disabilities (ID) might be due to a deficit in verbal rehearsal. However, the evidence is inconclusive and word length effects as indicator of rehearsal have been criticised. Aim amp; method: The aim of this multi-site European study was to investigate verbal rehearsal in adolescents with mild ID (n = 90) and a comparison group of typically developing children matched individually for mental age (MA, n = 90). The investigation involved: (1) a word length experiment with non-verbal recall using pointing and (2) self-paced inspection times to infer whether verbal strategies were utilised when memorising a set of pictorial items. Results: The word length effect on recall did not interact with group, suggesting that adolescents with ID and MA comparisons used similar verbal strategies, possibly phonological recoding of picture names. The inspection time data suggested that high span individuals in both groups used verbal labelling or single item rehearsal on more demanding lists, as long named items had longer inspection times. Conclusions: The findings suggest that verbal strategy use is not specifically impaired in adolescents with mild ID and is mental age appropriate, supporting a developmental perspective. (C) 2016 Elsevier Ltd. All rights reserved.
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