Publications by authors named "Donald Warden"

Background: Increasing syphilis infection rates are a concerning issue worldwide. Blood donation screening is an opportunity to monitor the burden of asymptomatic infections, providing information on contemporary factors associated with infection and public health insights into transmission.

Methods: Blood donations collected at five Brazilian blood centers between January 2020 and February 2022 were screened with treponemal or non-treponemal assays according to local protocols, followed by alternate Enzyme-Linked Immunosorbent Assay (ELISA); samples with reactive or indeterminate results in the alternate ELISA were further tested with the rapid plasma reagin (RPR), and categorized as RPR-positive or RPR-negative.

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Background: Pollen exposure is an environmental risk factor for asthma symptoms and allergic reactions in children. The extent to which pollen exposure in pregnancy and the first year of life influences the development of childhood asthma and rhinitis is not fully understood.

Objective: We aimed to investigate early life exposures to pollen with childhood asthma and rhinitis at age 6 in a longitudinal birth cohort of the United Kingdom.

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Serial blood and mucosal samples were characterized for 102 participants enrolled a median of 7.0 days after coronavirus disease 2019 diagnosis. Mucosal RNA was detectable for a median of 31.

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Background: Accurate diagnosis of Alzheimer disease (AD) involving less invasive molecular procedures and at reasonable cost is an unmet medical need. We identified a serum miRNA signature for AD that is less invasive than a measure in cerebrospinal fluid.

Methods: From the Oxford Project to Investigate Memory and Aging (OPTIMA) study, 96 serum samples were profiled by a multiplex (>500 analytes) microRNA (miRNA) reverse transcription quantitative PCR analysis, including 51 controls, 32 samples from patients with AD, and 13 samples from patients with mild cognitive impairment (MCI).

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Article Synopsis
  • An amendment to the original paper has been released.
  • You can find the amendment through a link provided at the top of the paper.
  • This update may contain important changes or additional information related to the original content.
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Pre-synaptic secretion of brain-derived neurotrophic factor (BDNF) from noradrenergic neurons may protect the Alzheimer's disease (AD) brain from amyloid pathology. While the BDNF polymorphism (rs6265) is associated with faster cognitive decline and increased hippocampal atrophy, a replicable genetic association of BDNF with AD risk has yet to be demonstrated. This could be due to masking by underlying epistatic interactions between BDNF and other loci that encode proteins involved in moderating BDNF secretion (DBH and Sortilin).

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Low homocysteine levels and B vitamin treatment are reported to protect against declining cognitive health. Both B vitamins and homocysteine are involved in the production of S-adenosylmethionine, a universal methyl donor essential for the process of DNA methylation. We investigated the effect of a damaging coding variant within the DNA methyltransferase gene DNMT3L (R278G, A/G) by examining B vitamin intake, homocysteine levels, cognitive performance, and brain atrophy in individuals in the VITACOG study of mild cognitive impairment and the TwinsUK cohort.

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Article Synopsis
  • Late-onset Alzheimer's disease (LOAD) is the most common type of dementia and is influenced by genetics.
  • Researchers studied a lot of people (94,437) to find specific genes that may increase the risk of developing LOAD, confirming 20 known ones and discovering 5 new ones.
  • They also found that certain genetic traits related to the immune system and how the brain processes proteins are linked to a higher risk of LOAD, suggesting there are more rare genes yet to be identified that could also play a role.
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Cerebral amyloid angiopathy (CAA) is of increasing clinical and research interest as the ability to detect it and its consequences by neuroimaging in living subjects has advanced. There is also increasing interest in understanding its possible role in the development of intracerebral hemorrhage, Alzheimer's disease (AD) and vascular dementia. In this article, the literature on this subject is reviewed and novel findings relating CAA to subcortical white matter damage in 224 subjects in the Oxford project to Investigate Memory and Ageing (OPTIMA) are reported.

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Previous mass spectrometry analysis of cerebrospinal fluid (CSF) has allowed the identification of a panel of molecular markers that are associated with Alzheimer's disease (AD). The panel comprises Amyloid beta, Apolipoprotein E, Fibrinogen alpha chain precursor, Keratin type I cytoskeletal 9, Serum albumin precursor, SPARC-like 1 protein and Tetranectin. Here we report the development and implementation of immunoassays to measure the abundance and diagnostic capacity of these putative biomarkers in matched lumbar CSF and blood plasma samples taken in life from individuals confirmed at post-mortem as suffering from AD (n = 10) and from screened 'cognitively healthy' subjects (n = 18).

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Epistasis between interleukin-10 (IL10) and aromatase gene polymorphisms has previously been reported to modify the risk of Alzheimer's disease (AD). However, although the main effects of aromatase variants suggest a sex-specific effect in AD, there has been insufficient power to detect sex-specific epistasis between these genes to date. Here we used the cohort of 1757 AD patients and 6294 controls in the Epistasis Project.

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Despite recent discoveries in the genetics of sporadic Alzheimer's disease, there remains substantial "hidden heritability." It is thought that some of this missing heritability may be because of gene-gene, i.e.

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Objective: Neuroinflammation contributes to the pathogenesis of sporadic Alzheimer's disease (AD). Variations in genes relevant to inflammation may be candidate genes for AD risk. Whole-genome association studies have identified relevant new and known genes.

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Altered glucose metabolism has been described in Alzheimer's disease (AD). We re-investigated the interaction of the insulin (INS) and the peroxisome proliferator-activated receptor alpha (PPARA) genes in AD risk in the Epistasis Project, including 1,757 AD cases and 6,294 controls. Allele frequencies of both SNPs (PPARA L162V, INS intron 0 A/T) differed between Northern Europeans and Northern Spanish.

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We have used proteomic fingerprinting to investigate diagnosis of Alzheimer's disease (AD). Samples of lumbar cerebrospinal fluid (CSF) from clinically-diagnosed AD cases (n = 33), age-matched controls (n = 20), and mild cognitive impairment (MCI) patients (n = 10) were used to obtain proteomic profiles, followed by bioinformatic analysis that generated a set of potential biomarkers in CSF samples that could discriminate AD cases from controls. The identity of the biomarker ions was determined using mass spectroscopy.

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Vitamin D may have a role in brain function. Low levels have been frequently associated with cognitive decline and may contribute to diseases of the nervous system. The vitamin D receptor (VDR) is widely expressed in human brain.

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We sought to identify new susceptibility loci for Alzheimer's disease through a staged association study (GERAD+) and by testing suggestive loci reported by the Alzheimer's Disease Genetic Consortium (ADGC) in a companion paper. We undertook a combined analysis of four genome-wide association datasets (stage 1) and identified ten newly associated variants with P ≤ 1 × 10(-5). We tested these variants for association in an independent sample (stage 2).

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A key pathological feature of late-onset Alzheimer's disease (LOAD) is the abnormal extracellular accumulation of the amyloid-β (Aβ) peptide. Thus, altered Aβ degradation could be a major contributor to the development of LOAD. Variants in the gene encoding the Aβ-degrading enzyme, angiotensin-1 converting enzyme (ACE) therefore represent plausible candidates for association with LOAD pathology and risk.

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Article Synopsis
  • The study investigates the link between a specific genetic variant of dopamine β-hydroxylase (DBH -1021T allele) and the risk of developing Alzheimer's disease (AD), finding a notable association, especially in men under 75 years old.
  • It also reveals that this variant interacts with certain polymorphisms in pro-inflammatory cytokine genes (IL1A and IL6), which may increase the risk of AD through inflammatory misregulation.
  • The findings highlight the potential role of noradrenaline in inflammation control in the brain and suggest that the low activity of the DBH -1021T allele might contribute to the development of Alzheimer's.
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Iron overload may contribute to the risk of Alzheimer's disease (AD). In the Epistasis Project, with 1757 cases of AD and 6295 controls, we studied 4 variants in 2 genes of iron metabolism: hemochromatosis (HFE) C282Y and H63D, and transferrin (TF) C2 and -2G/A. We replicated the reported interaction between HFE 282Y and TF C2 in the risk of AD: synergy factor, 1.

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Background: The insulin-degrading enzyme gene (IDE) is a strong functional and positional candidate for late onset Alzheimer's disease (LOAD).

Methodology/principal Findings: We examined conserved regions of IDE and its 10 kb flanks in 269 AD cases and 252 controls thereby identifying 17 putative functional polymorphisms. These variants formed eleven haplotypes that were tagged with ten variants.

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Associations have been reported of aromatase polymorphisms with Alzheimer's disease (AD). We studied nine polymorphisms in 207 cases of AD, 23 cases of mild cognitive impairment (MCI) and 233 controls, all from the OPTIMA cohort. We replicated two reported associations and found others.

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Background: Chronic inflammation is a characteristic of Alzheimer's disease (AD). An interaction associated with the risk of AD has been reported between polymorphisms in the regulatory regions of the genes for the pro-inflammatory cytokine, interleukin-6 (IL-6, gene: IL6), and the anti-inflammatory cytokine, interleukin-10 (IL-10, gene: IL10).

Methods: We examined this interaction in the Epistasis Project, a collaboration of 7 AD research groups, contributing DNA samples from 1,757 cases of AD and 6,295 controls.

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There is evidence to suggest an involvement of the K variant of the butyrylcholinesterase gene (BCHE) in dementia. We have examined the relationship between BCHE genotype and butyrylcholinesterase (BuChE) activity in autopsy brain tissue. We studied 164 autopsy cases, 144 with dementia and 20 controls, including 13 K homozygotes and 48 K heterozygotes, from three centres: Newcastle, Oxford and London.

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Mutations in amyloid precursor protein (APP) and presenilin (PSEN) genes are known to cause familial early-onset Alzheimer's disease (AD), which account for around 5% of AD cases. Genetic associations for the remaining "sporadic" cases, other than the risks associated with the apolipoprotein (APOE) epsilon4 allele are currently not fully established. The aim of this study was to investigate whether single nucleotide polymorphisms (SNPs) in PSEN1 are associated with a modified risk for sporadic AD or a modified disease phenotype.

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