Publications by authors named "Alexandra Nicholson"

Genetic frontotemporal lobar degeneration caused by autosomal dominant gene mutations provides an opportunity for targeted drug development in a highly complex and clinically heterogeneous dementia. These neurodegenerative disorders can affect adults in their middle years, progress quickly relative to other dementias, are uniformly fatal and have no approved disease-modifying treatments. Frontotemporal dementia, caused by mutations in the gene which encodes the protein progranulin, is an active area of interventional drug trials that are testing multiple strategies to restore progranulin protein deficiency.

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TMEM106B has been recently implicated in multiple neurodegenerative diseases. Here, Rademakers et al. report a late-onset cerebellar Purkinje cell loss and progressive decline in motor function and gait deficits in a conventional Tmem106b-/- mouse model.

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Genetic variants that define two distinct haplotypes at the TMEM106B locus have been implicated in multiple neurodegenerative diseases and in healthy brain ageing. In frontotemporal dementia (FTD), the high expressing TMEM106B risk haplotype was shown to increase susceptibility for FTD with TDP-43 inclusions (FTD-TDP) and to modify disease penetrance in progranulin mutation carriers (FTD-GRN). To elucidate the biological function of TMEM106B and determine whether lowering TMEM106B may be a viable therapeutic strategy, we performed brain transcriptomic analyses in 8-month-old animals from our recently developed Tmem106b-/- mouse model.

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Background: Loss of function mutations in progranulin (GRN) are a major cause of frontotemporal dementia (FTD). Progranulin is a secreted glycoprotein that localizes to lysosomes and is critical for proper lysosomal function. Heterozygous GRN mutation carriers develop FTD with TDP-43 pathology and exhibit signs of lysosomal dysfunction in the brain, with increased levels of lysosomal proteins and lipofuscin accumulation.

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Loss-of-function mutations in progranulin (GRN) and a non-coding (GGGGCC) hexanucleotide repeat expansions in C9ORF72 are the two most common genetic causes of frontotemporal lobar degeneration with aggregates of TAR DNA binding protein 43 (FTLD-TDP). TMEM106B encodes a type II transmembrane protein with unknown function. Genetic variants in TMEM106B associated with reduced TMEM106B levels have been identified as disease modifiers in individuals with GRN mutations and C9ORF72 expansions.

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Introduction: There is growing recognition in the health community that the legal environment-including laws, policies, and related procedures-impacts vulnerability to HIV and access to HIV-related services both positively and negatively. Assessing changes in the legal environment and how these affect HIV-related outcomes, however, is challenging, and understanding of appropriate methodologies nascent.

Methods: We conducted an evaluation of a UNDP project designed to strengthen legal environments to support the human rights of key populations, in particular LGBT populations, women and girls, affected by HIV in sub-Saharan Africa.

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Objective: The last few years have seen a rise in the number of global and national initiatives that seek to incorporate human rights into public health practice. Nonetheless, a lack of clarity persists regarding the most appropriate indicators to monitor rights concerns in these efforts. The objective of this work was to develop a systematic methodology for use in determining the extent to which indicators commonly used in public health capture human rights concerns, using contraceptive services and programmes as a case study.

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Mutations in the stress granule protein T-cell restricted intracellular antigen 1 (TIA1) were recently shown to cause amyotrophic lateral sclerosis (ALS) with or without frontotemporal dementia (FTD). Here, we provide detailed clinical and neuropathological descriptions of nine cases with TIA1 mutations, together with comparisons to sporadic ALS (sALS) and ALS due to repeat expansions in C9orf72 (C9orf72+). All nine patients with confirmed mutations in TIA1 were female.

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Background: Surgical site infections (SSIs) are the third most common hospital-associated infection and can lead to significant patient morbidity and healthcare costs. Identification of SSIs is key to surveillance and research but reliable assessment is challenging, particularly after hospital discharge when most SSIs present. Existing SSI measurement tools have limitations and their suitability for post-discharge surveillance is uncertain.

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Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are age-related neurodegenerative disorders with shared genetic etiologies and overlapping clinical and pathological features. Here we studied a novel ALS/FTD family and identified the P362L mutation in the low-complexity domain (LCD) of T cell-restricted intracellular antigen-1 (TIA1). Subsequent genetic association analyses showed an increased burden of TIA1 LCD mutations in ALS patients compared to controls (p = 8.

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Article Synopsis
  • - We conducted a genome-wide brain expression study to investigate diseases linked to a specific repeat expansion in chromosome 9 by analyzing brain tissue from expansion carriers, non-carriers, and controls.
  • - Our analysis revealed significant changes in gene expression in the cerebellum, identifying 40 genes, including several homeobox genes crucial for neuronal development, and the neuroprotective protein transthyretin.
  • - These findings highlight potential compensatory mechanisms involving developmental and neuroprotective genes that may influence the occurrence and progression of diseases related to the repeat expansion.
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Frontotemporal lobar degeneration is a neurodegenerative disorder affecting over 50,000 people in the United States alone. The most common pathological subtype of FTLD is the presence of ubiquitinated TAR DNA binding protein 43 (TDP-43) accumulations in frontal and temporal brain regions at autopsy. While some cases of FTLD-TDP can be attributed to the inheritance of disease-causing mutations, the majority of cases arise with no known genetic cause.

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Mutations in progranulin are a major cause of frontotemporal lobe degeneration (FTLD). Hence, plasma progranulin is an attractive biomarker in FTLD but poorly reflects levels in cerebrospinal fluid (CSF), suggesting tissue-specific regulation of progranulin levels. Sortilin was recently identified as a progranulin scavenger receptor that destines it for lysosomal degradation.

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Progranulin (GRN) loss-of-function mutations leading to progranulin protein (PGRN) haploinsufficiency are prevalent genetic causes of frontotemporal dementia. Reports also indicated PGRN-mediated neuroprotection in models of Alzheimer's and Parkinson's disease; thus, increasing PGRN levels is a promising therapeutic for multiple disorders. To uncover novel PGRN regulators, we linked whole-genome sequence data from 920 individuals with plasma PGRN levels and identified the prosaposin (PSAP) locus as a new locus significantly associated with plasma PGRN levels.

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Objective: To undertake a systematic review and meta-analysis to establish the effectiveness of handwashing in reducing absence and/or the spread of respiratory tract (RT) and/or gastrointestinal (GI) infection among school-aged children and/or staff in educational settings.

Design: Randomised-controlled trials (RCTs).

Setting: Schools and other settings with a formal educational component in any country.

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Frontotemporal lobar degeneration with TAR DNA-binding protein 43 inclusions (FTLD-TDP) is the most common pathology associated with frontotemporal dementia (FTD). Repeat expansions in chromosome 9 open reading frame 72 (C9ORF72) and mutations in progranulin (GRN) are the major known genetic causes of FTLD-TDP; however, the genetic etiology in the majority of FTLD-TDP remains unexplained. In this study, we performed whole-genome sequencing in 104 pathologically confirmed FTLD-TDP patients from the Mayo Clinic brain bank negative for C9ORF72 and GRN mutations and report on the contribution of rare single nucleotide and copy number variants in 21 known neurodegenerative disease genes.

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Article Synopsis
  • Three genes linked to idiopathic basal ganglia calcification (IBGC) were identified, particularly noting the role of mutations in PDGFRB and PDGFB in abnormal brain calcification.*
  • In a study involving 26 patients with unknown causes of basal ganglia calcification, a mutation in PDGFRB was found, while no mutations in PDGFB were detected.*
  • Functional analysis of three PDGFRB mutations indicated that p.L658P suppresses autophosphorylation, p.R695C causes partial loss of function, and p.R987W is linked to reduced protein levels, supporting the idea that PDGFRB mutations contribute to the disease.*
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Objective: We aimed to investigate the relationship between plasma and CSF progranulin (PGRN) levels.

Methods: Plasma and CSF PGRN were measured in a cohort of 345 subjects from the Mayo Clinic Study of Aging by ELISA. Single nucleotide polymorphism genotyping was performed using TaqMan assays.

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Variants in transmembrane protein 106 B (TMEM106B) modify the disease penetrance of frontotemporal dementia (FTD) in carriers of progranulin (GRN) mutations. We investigated whether TMEM106B is also a genetic modifier of disease in carriers of chromosome 9 open reading frame 72 (C9ORF72) expansions. We assessed the genotype of 325 C9ORF72 expansion carriers (cohort 1), 586 FTD patients lacking C9ORF72 expansions [with or without motor neuron disease (MND); cohort 2], and a total of 1,302 controls for TMEM106B variants (rs3173615 and rs1990622) using MassArray iPLEX and Taqman genotyping assays.

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Background: Process evaluations are useful for understanding how interventions are implemented in trial settings. This is important for interpreting main trial results and indicating how the intervention might function beyond the trial. The purpose of this study was to examine the reach, dose, fidelity, acceptability, and sustainability of the implementation of an educational hand washing intervention in primary schools, and to explore views regarding acceptability and sustainability of the intervention.

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Atypical Parkinsonism associated with white matter pathology has been described in cerebrovascular diseases, mitochondrial cytopathies, osmotic demyelinating disorders, leukoencephalopathies leukodystrophies, and others. Hereditary diffuse leukoencephalopathy with spheroids (HDLS) is an autosomal dominant disorder with symptomatic onset in midlife and death within a few years after symptom onset. Neuroimaging reveals cerebral white matter lesions that are pathologically characterized by non-inflammatory myelin loss, reactive astrocytosis, and axonal spheroids.

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Frontotemporal lobar degeneration (FTLD) is the second leading cause of dementia in individuals under age 65. In many patients, the predominant pathology includes neuronal cytoplasmic or intranuclear inclusions of ubiquitinated TAR DNA binding protein 43 (FTLD-TDP). Recently, a genome-wide association study identified the first FTLD-TDP genetic risk factor, in which variants in and around the TMEM106B gene (top SNP rs1990622) were significantly associated with FTLD-TDP risk.

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Objective: Pigmented orthochromatic leukodystrophy (POLD) and hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS) are rare neurodegenerative disorders characterized by cerebral white matter abnormalities, myelin loss, and axonal swellings. The striking overlap of clinical and pathologic features of these disorders suggested a common pathogenesis; however, no genetic or mechanistic link between POLD and HDLS has been established. Recently, we reported that mutations in the colony-stimulating factor 1 receptor (CSF1R) gene cause HDLS.

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