Publications by authors named "David Dimasi"

Article Synopsis
  • The study aimed to investigate the relationship between the apolipoprotein E (E4) allele and the prevalence of glaucoma in large genetic cohorts, including data from over 438,000 participants in the UK Biobank and several other studies.* -
  • Results indicated that the E4 allele was inversely associated with glaucoma and negative control conditions like cataract and diabetic eye disease in the UK Biobank, suggesting a potential protective effect.* -
  • However, a separate association was found linking Alzheimer's dementia (AD) with both glaucoma and cataract, indicating complexities in the relationship between E4 and these eye conditions, with replication analyses failing to confirm initial findings.*
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Purpose: To investigate the association between the apolipoprotein E () E4 dementia-risk allele and prospective longitudinal retinal thinning in a cohort study of suspect and early manifest glaucoma.

Design: Retrospective analysis of prospective cohort data.

Participants: This study included all available eyes from participants recruited to the Progression Risk of Glaucoma: Relevant SNPs [single nucleotide polymorphisms] with Significant Association (PROGRESSA) study with genotyping data from which genotypes could be determined.

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Purpose: Pseudoexfoliation syndrome (PEX) is a common systemic disease that results in severe and often irreversible vision loss. Despite considerable research effort, PEX remains incompletely understood. This study sought to perform the first RNAseq study in elucidate the pathophysiology of PEX, and contribute a publicly available transcriptomic data resource for future research.

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Background: Inflammatory Bowel Disease (IBD) is characterized by overt inflammation of the intestine and is typically accompanied by symptoms of bloody diarrhea, abdominal pain and cramping. The Colonic Migrating Motor Complex (CMMC) directs the movement of colonic luminal contents over long distances. The tri-nitrobenzene sulphonic acid (TNBS) model of colitis causes inflammatory damage to enteric nerves, however it remains to be determined whether these changes translate to functional outcomes in CMMC activity.

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  • The study investigates the potential link between bolus intravenous (i.v.) fluid administration and acute lung injury using rat models, aiming to uncover the mechanisms involved.
  • Healthy rats given saline i.v. showed increased lung water and inflammation, along with worse lung function, which was tied to the activation of TRPV4 channels.
  • Findings indicated that blocking TRPV4 with ruthenium red reduced lung injury, suggesting that TRPV4 channel activation and endothelial inflammatory responses are key factors in fluid-induced lung edema.
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The prevalence of allergies, including rhinitis, eczema, and anaphylaxis, is rising dramatically worldwide. This increase is especially problematic in children who bear the greatest burden of this rising trend. Increasing evidence identifies neutrophils as primary perpetrators of the more severe and difficult to manage forms of inflammation.

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Objective: A key mediator of vascular EC barrier integrity, S1P, is derived from phosphorylation of sphingosine by the SK-1 and SK-2. While previous work indicates that SK-1 can regulate EC barrier integrity, whether SK-2 has a similar role remains to be determined.

Methods: A cell impedance assay was used to assess human umbilical vein EC and bone marrow EC barrier integrity in vitro, with application of the SK inhibitors ABC294640, PF543, SKi, and MP-A08.

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Although endothelial cell (EC) infection is not widespread during dengue virus (DENV) infection in vivo, the endothelium is the site of the pathogenic effects seen in severe DENV disease. In this study, we investigated DENV infection of primary EC and defined factors that influence infection in this cell type. Consistent with in vivo findings where EC infection is infrequent, only 3%-15% of EC became productively DENV-2-infected in vitro.

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It has recently been shown that there are highly significant associations for common single nucleotide polymorphisms (SNPs) near the CDKN2B-AS1 gene region at the 9p21 locus with primary open angle glaucoma (POAG), a leading cause of irreversible blindness. This gene region houses the CDKN2B/p15(INK4B) , CDKN2A/p16(INK4A) and p14ARF (rat equivalent, p19(ARF) ) tumour suppressor genes and is adjacent to the S-methyl-5'-thioadenosine phosphorylase (MTAP) gene. In order to understand the ocular function of these genes and, therefore, how they may be involved in the pathogenesis of POAG, we studied the distribution patterns of each of their products within human and rat ocular tissues.

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Neutrophils are a key mediator of the innate immune system and are pivotal in the inflammatory response to infection or tissue damage. Fundamental to the role that neutrophils play in host defence is their interaction with the vascular endothelium. From the initial mobilisation of neutrophils out of the bone marrow to their ultimate transmigration through the vasculature, endothelial cells are a vital component of the inflammatory process.

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Article Synopsis
  • * A meta-analysis of over 20,000 people found 16 new genetic locations associated with CCT, including two key loci (FOXO1 and FNDC3B) that significantly increase the risk for keratoconus.
  • * FNDC3B was also linked to primary open-angle glaucoma, suggesting that collagen and extracellular matrix pathways are important in regulating CCT.
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Background: Loss of vision in glaucoma is due to apoptotic retinal ganglion cell loss. While p53 modulates apoptosis, gene association studies between p53 variants and glaucoma have been inconsistent. In this study we evaluate the association between a p53 variant functionally known to influence apoptosis (codon 72 Pro/Arg) and the subset of primary open angle glaucoma (POAG) patients with early loss of central visual field.

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Purpose: To ascertain if single nucleotide polymorphisms (SNPs) involved in the determination of central corneal thickness, optic disc area, and vertical cup-to-disc ratio (VCDR) also are associated with open-angle glaucoma (OAG).

Design: Retrospective case-control genetic association study.

Methods: A total of 16 SNPs associated with central corneal thickness, optic disc area, and VCDR were genotyped in 876 OAG cases and 883 normal controls.

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Purpose: Glaucoma is the leading cause of irreversible blindness worldwide. Primary open angle glaucoma (POAG) is the most common subtype. We recently reported association of genetic variants at chromosomal loci, 1q24 and 9p21, with POAG.

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The cornea is a transparent structure that permits the refraction of light into the eye. Evidence from a range of studies indicates that central corneal thickness (CCT) is strongly genetically determined. Support for a genetic component comes from data showing significant variation in CCT between different human ethnic groups.

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Central corneal thickness (CCT), one of the most highly heritable human traits (h(2) typically>0.9), is important for the diagnosis of glaucoma and a potential risk factor for glaucoma susceptibility. We conducted genome-wide association studies in five cohorts from Australia and the United Kingdom (total N = 5058).

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Purpose: The genetic component underlying variation in central corneal thickness (CCT) in the normal population remains largely unknown. As CCT is an identified risk factor for open-angle glaucoma, understanding the genes involved in CCT determination could improve our understanding of the mechanisms involved in this association.

Methods: To identify novel CCT genes, we selected eight different candidates based on a range of criteria.

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Osteogenesis imperfecta (OI) is a rare connective tissue disorder caused by mutations in the type I collagen genes, COL1A1 and COL1A2, and is characterised by low bone mass and bone fragility. In this study, we explored the relationship between type 1 collagen genes and the quantitative trait central corneal thickness (CCT). CCT was measured in a cohort of 28 Australian type I OI patients and mean CCT was found to be significantly lower compared to a normal population (P < 0.

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Purpose: Many ocular parameters show strong heritable tendencies. The significance of central corneal thickness (CCT) in the context of glaucoma has been the subject of much debate recently, but its heritability has not been extensively explored. This study was designed to investigate the parent-child heritability of CCT among groups who have CCT considered to be at the extreme ends of the normal range.

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Purpose: A Tyr-to-His (Y402H) sequence variant in the factor H (FH) and factor H-like protein (FHL-1) gene is strongly associated with an increased susceptibility for age-related macular degeneration (AMD). The purpose of this study was to understand how the Y402H variant in FH/FHL-1 contributes to the pathogenesis of AMD and, in particular, whether interactions mediated by FH/FHL-1, including binding to C-reactive protein (CRP), group A streptococcal M protein (GAS M6), heparin, and retinal pigment epithelial cells (RPE), are affected.

Methods: FH was purified from sera of patients homozygous for FH(Y402) or (H402), and recombinant FH fragments representing FHL-1 were generated.

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Pseudoexfoliation syndrome is a generalized disorder of the extracellular matrix, characterized by the pathological accumulation of abnormal fibrillar material in the anterior segment of the eye predisposing to glaucomatous optic neuropathy. We investigated the role of lysyl oxidase-like 1(LOXL1) sequence variation in a Caucasian Australian population-based cohort of 2508 individuals, 86 (3.4%) of whom were diagnosed with pseudoexfoliation syndrome.

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Purpose: To report the presence of dense and abnormal iris processes in the unaffected parents and sibling of a non consanguineous family where 3 children out of 4 suffer from primary infantile glaucoma (PIG).

Methods: A descriptive case report. All family members were clinically characterized.

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Hereditary hyperferritinemia cataract syndrome (HHCS) is characterized by distinctive cataracts and high serum ferritin in the absence of iron overload. It is caused by mutations in the iron response element (IRE) of the Ferritin Light Chain (FTL) gene. Here we investigate the genetics of HHCS in a three generation Australian kindred with typical HHCS ocular lens morphology and high ferritin levels.

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The retina and retinal pigment epithelium (RPE) are present in the posterior segment of the eye, and the retina is dependent upon the underlying RPE for normal function. The retina is the most oxygenated tissue in the body but is isolated from the blood circulation by blood-retinal barriers. Metabolism of cellular oxygen involves heme but little is known about heme transport in the retina and RPE.

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Objective: To determine the phenotype of an Australian pedigree with the myocilin (MYOC) Gly252Arg mutation, comparing it with other pedigrees carrying the same mutation.

Methods: All recruited subjects underwent a comprehensive clinical examination, including optic disc assessment, applanation tonometry, and visual field measurement. Mutation analysis was performed through direct sequencing.

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