51
|
Le Marois A, Labouesse S, Suhling K, Heintzmann R. Noise-Corrected Principal Component Analysis of fluorescence lifetime imaging data. JOURNAL OF BIOPHOTONICS 2017; 10:1124-1133. [PMID: 27943625 DOI: 10.1002/jbio.201600160] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 09/23/2016] [Accepted: 11/14/2016] [Indexed: 05/08/2023]
Abstract
Fluorescence Lifetime Imaging (FLIM) is an attractive microscopy method in the life sciences, yielding information on the sample otherwise unavailable through intensity-based techniques. A novel Noise-Corrected Principal Component Analysis (NC-PCA) method for time-domain FLIM data is presented here. The presence and distribution of distinct microenvironments are identified at lower photon counts than previously reported, without requiring prior knowledge of their number or of the dye's decay kinetics. A noise correction based on the Poisson statistics inherent to Time-Correlated Single Photon Counting is incorporated. The approach is validated using simulated data, and further applied to experimental FLIM data of HeLa cells stained with membrane dye di-4-ANEPPDHQ. Two distinct lipid phases were resolved in the cell membranes, and the modification of the order parameters of the plasma membrane during cholesterol depletion was also detected. Noise-corrected Principal Component Analysis of FLIM data resolves distinct microenvironments in cell membranes of live HeLa cells.
Collapse
Affiliation(s)
- Alix Le Marois
- Department of Physics, King's College London, Strand, WC2R 2LS, London, United Kingdom
| | - Simon Labouesse
- Institute Fresnel, Avenue Escadrille Normandie Niemen, 13013, Marseille, France
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Klaus Suhling
- Department of Physics, King's College London, Strand, WC2R 2LS, London, United Kingdom
| | - Rainer Heintzmann
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745, Jena, Germany
- Institute of Physical Chemistry, Abbe Centre of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
| |
Collapse
|
52
|
Sauer L, Peters S, Schmidt J, Schweitzer D, Klemm M, Ramm L, Augsten R, Hammer M. Monitoring macular pigment changes in macular holes using fluorescence lifetime imaging ophthalmoscopy. Acta Ophthalmol 2017; 95:481-492. [PMID: 27775222 DOI: 10.1111/aos.13269] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 08/12/2016] [Indexed: 01/19/2023]
Abstract
PURPOSE To investigate the impact of macular pigment (MP) on fundus autofluorescence (FAF) lifetimes in vivo by characterizing full-thickness idiopathic macular holes (MH) and macular pseudo-holes (MPH). METHODS A total of 37 patients with MH and 52 with MPH were included. Using the fluorescence lifetime imaging ophthalmoscope (FLIO), based on a Heidelberg Engineering Spectralis system, a 30° retinal field was investigated. FAF decays were detected in a short (498-560 nm; ch1) and long (560-720 nm; ch2) wavelength channel. τm , the mean fluorescence lifetime, was calculated from a three-exponential approximation of the FAF decays. Macular coherence tomography scans were recorded, and macular pigment's optical density (MPOD) was measured (one-wavelength reflectometry). Two MH subgroups were analysed according to the presence or absence of an operculum above the MH. A total of 17 healthy fellow eyes were included. A longitudinal FAF decay examination was conducted in nine patients, which were followed up after surgery and showed a closed MH. RESULTS In MH without opercula, significant τm differences (p < 0.001) were found between the hole area (MHa) and surrounding areas (MHb) (ch1: MHa 238 ± 64 ps, MHb 181 ± 78 ps; ch2: MHa 275 ± 49 ps, MHb 223 ± 48 ps), as well as between MHa and healthy eyes or closed MH. Shorter τm , adjacent to the hole, can be assigned to areas with equivalently higher MPOD. Opercula containing MP also show short τm . In MPH, the intactness of the Hele fibre layer is associated with shortest τm . CONCLUSIONS Shortest τm originates from MP-containing retinal layers, especially from the Henle fibre layer. Fluorescence lifetime imaging ophthalmoscope (FLIO) provides information on the MP distribution, the pathogenesis and topology of MH. Macular pigment (MP) fluorescence may provide a biomarker for monitoring pathological changes in retinal diseases.
Collapse
Affiliation(s)
- Lydia Sauer
- Department of Ophthalmology; University Hospital Jena; Jena Germany
| | - Sven Peters
- Department of Ophthalmology; University Hospital Jena; Jena Germany
| | - Johanna Schmidt
- Department of Ophthalmology; University Hospital Jena; Jena Germany
| | | | - Matthias Klemm
- Institute of Biomedical Engineering and Informatics; Technical University Ilmenau; Ilmenau Germany
| | - Lisa Ramm
- Department of Ophthalmology; University Hospital Carl-Gustav Carus; TU Dresden Germany
| | - Regine Augsten
- Department of Ophthalmology; University Hospital Jena; Jena Germany
| | - Martin Hammer
- Department of Ophthalmology; University Hospital Jena; Jena Germany
- Center for Medical Optics and Photonics; University of Jena; Jena Germany
| |
Collapse
|
53
|
Xie B, Liu F, Dong X, Wang Y, Liu XM, Sun Y. Modulation effect of acidulated human serum albumin on Cu 2+ -mediated amyloid β-protein aggregation and cytotoxicity under a mildly acidic condition. J Inorg Biochem 2017; 171:67-75. [DOI: 10.1016/j.jinorgbio.2017.03.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Revised: 02/10/2017] [Accepted: 03/19/2017] [Indexed: 12/31/2022]
|
54
|
Afonso JM, Falcão M, Schlichtenbrede F, Falcão-Reis F, Silva SE, Schneider TM. Spectral Domain-Optical Coherence Tomography As a New Diagnostic Marker for Idiopathic Normal Pressure Hydrocephalus. Front Neurol 2017; 8:172. [PMID: 28507532 PMCID: PMC5410594 DOI: 10.3389/fneur.2017.00172] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Accepted: 04/12/2017] [Indexed: 11/13/2022] Open
Abstract
PURPOSE Characterized by a progressive onset of gait disturbances, dementia, and urinary incontinence, idiopathic normal pressure hydrocephalus (iNPH) is considered a rare, but under-diagnosed disease. Non-invasive diagnostic markers are still insufficient to enable the diagnosis of iNPH with certainty and yet early treatment with ventriculoperitoneal (VP) shunting can reverse symptoms and stop disease progression. Vascular circulation abnormalities in iNPH may be reflected by changes in subfoveal and peripapillary choroidal thickness (PPChT). This study uses spectral domain-optical coherence tomography (SD-OCT)-based measures of retinal and choroidal thickness to test this hypothesis and to assess ophthalmological non-invasive markers for iNPH. METHODS Twelve patients who displayed neurological and neuroradiological characteristics of iNPH were subject to a full ophthalmological examination including enhanced depth imaging (EDI) SD-OCT. Of the 12 included iNPH patients, 6 had undergone VP shunting with beneficial outcome. Parameters studied with EDI SD-OCT were macular retinal thickness (MT), subfoveal choroidal thickness (SFChT), retinal nerve fiber layer thickness (RNFL), and PPChT. Results were compared with 13 healthy, age-matched controls. RESULTS Macular thickness and RNFL and MT values of iNPH patients did not reflect atrophy. Non-shunted iNPH patients showed significantly lowered median PPChT and SFChT values compared to healthy controls. Shunted iNPH patients displayed a significantly higher median PPChT and SFChT compared to non-shunted iNPH patients. SFChT and PPChT values in shunted patients were not significantly different to values in healthy controls. CONCLUSION Although limited by small sample size, SD-OCT measures in this study reveal significant changes of choroidal thickness and support the hypothesis of choroidal susceptibility to hemodynamic alterations in iNPH. Non-shunted iNPH patients in this study show choroidal thinning in combination with normal RNFL and MT values. In addition to neurological and neuroradiological exams, this pattern may aid in the challenging diagnosis of iNPH.
Collapse
Affiliation(s)
- Joana M Afonso
- Department of Ophthalmology, São João University Hospital, Porto, Portugal.,Department of Ophthalmology, University Hospital Mannheim, Mannheim, Germany
| | - Manuel Falcão
- Department of Ophthalmology, São João University Hospital, Porto, Portugal.,Faculty of Medicine, Department of Sense Organs, University of Porto, Porto, Portugal
| | | | - Fernando Falcão-Reis
- Department of Ophthalmology, São João University Hospital, Porto, Portugal.,Faculty of Medicine, Department of Sense Organs, University of Porto, Porto, Portugal
| | | | - Till M Schneider
- Department of Neuroradiology, University Hospital Heidelberg, Heidelberg, Germany
| |
Collapse
|
55
|
Yakovleva MA, Feldman TB, Arbukhanova PM, Borzenok SA, Kuzmin VA, Ostrovsky MA. Estimation of fluorescence lifetime of lipofuscin fluorophores contained in lipofuscin granules of retinal pigment epithelium of human cadaver eyes without signs of pathology. DOKL BIOCHEM BIOPHYS 2017; 472:19-22. [DOI: 10.1134/s1607672917010069] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Indexed: 11/23/2022]
|
56
|
Beta-amyloid sequelae in the eye: a critical review on its diagnostic significance and clinical relevance in Alzheimer's disease. Mol Psychiatry 2017; 22:353-363. [PMID: 28093567 DOI: 10.1038/mp.2016.251] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 10/31/2016] [Accepted: 11/22/2016] [Indexed: 01/14/2023]
Abstract
Alzheimer's disease (AD) is a progressive and fatal neurodegenerative disorder. There is no test for its definitive diagnosis in routine clinical practice. Although phase III clinical trials have failed, only symptomatic treatment is currently available; a possible reason for these failed trials is that intervention commenced at an advanced stage of the disease. The hallmarks of an AD brain include plaques comprising of extracellular beta-amyloid (Aβ) protein aggregates and intracellular hyperphosphorylated neurofibrillary tangles of tau. Research into the preclinical diagnosis of AD has provided considerable evidence regarding early neuropathological changes using brain Aβ imaging and the cerebrospinal fluid biomarkers, Aβ and tau. Both these approaches have limitations that are expensive, invasive or time consuming and thus preclude them from screening at-risk population. Recent studies have demonstrated the presence of Aβ plaques in the eyes of AD subjects, which is positively associated with their brain Aβ burden. Thus ocular biomarkers point to a potential avenue for an earlier, relatively low-cost diagnosis in order for therapeutic interventions to be effective. Here we review the literature that spans the investigation for the presence of Aβ in aging eyes and the significance of its deposition in relation to AD pathology. We discuss clinical studies investigating in vivo imaging of Aβ in the eye and its association with brain Aβ burden and therapies that target ocular Aβ. Finally, we focus on the need to characterize AD-specific retinal Aβ to differentiate Aβ found in some eye diseases. Based on the current evidence, we conclude that integration of ocular biomarkers that can correctly predict brain Aβ burden would have an important role as a non-invasive, yet economical surrogate marker in the diagnostic process of AD.
Collapse
|
57
|
Cheung CYL, Ikram MK, Chen C, Wong TY. Imaging retina to study dementia and stroke. Prog Retin Eye Res 2017; 57:89-107. [PMID: 28057562 DOI: 10.1016/j.preteyeres.2017.01.001] [Citation(s) in RCA: 165] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 11/07/2016] [Accepted: 01/01/2017] [Indexed: 02/07/2023]
Abstract
With increase in life expectancy, the number of persons suffering from common age-related brain diseases, including neurodegenerative (e.g., dementia) and cerebrovascular (e.g., stroke) disease is expected to rise substantially. As current neuro-imaging modalities such as magnetic resonance imaging may not be able to detect subtle subclinical changes (resolution <100-500 μm) in dementia and stroke, there is an urgent need for other complementary techniques to probe the pathophysiology of these diseases. The retina - due to its anatomical, embryological and physiological similarities with the brain - offers a unique and accessible "window" to study correlates and consequences of subclinical pathology in the brain. Retinal components such as the microvasculature and retinal ganglion cell axons can now be visualized non-invasively using different retinal imaging techniques e.g., ocular fundus photography and optical coherence tomography. Advances in retinal imaging may provide new and potentially important insights into cerebrovascular neurodegenerative processes in addition to what is currently possible with neuro-imaging. In this review, we present an overview of the current literature on the application of retinal imaging in the study of dementia and stroke. We discuss clinical implications of these studies, novel state-of-the-art retinal imaging techniques and future directions aimed at evaluating whether retinal imaging can be an additional investigation tool in the study of dementia and stroke.
Collapse
Affiliation(s)
- Carol Yim-Lui Cheung
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong.
| | - M Kamran Ikram
- Duke-NUS Graduate Medical School, National University of Singapore, Singapore; Departments of Neurology & Epidemiology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Christopher Chen
- Memory Aging and Cognition Centre, National University Health System, Singapore; Department of Pharmacology, National University of Singapore, Singapore
| | - Tien Yin Wong
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore; Duke-NUS Graduate Medical School, National University of Singapore, Singapore
| |
Collapse
|
58
|
Hart NJ, Koronyo Y, Black KL, Koronyo-Hamaoui M. Ocular indicators of Alzheimer's: exploring disease in the retina. Acta Neuropathol 2016; 132:767-787. [PMID: 27645291 PMCID: PMC5106496 DOI: 10.1007/s00401-016-1613-6] [Citation(s) in RCA: 173] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 08/29/2016] [Accepted: 09/01/2016] [Indexed: 12/11/2022]
Abstract
Although historically perceived as a disorder confined to the brain, our understanding of Alzheimer's disease (AD) has expanded to include extra-cerebral manifestation, with mounting evidence of abnormalities in the eye. Among ocular tissues, the retina, a developmental outgrowth of the brain, is marked by an array of pathologies in patients suffering from AD, including nerve fiber layer thinning, degeneration of retinal ganglion cells, and changes to vascular parameters. While the hallmark pathological signs of AD, amyloid β-protein (Aβ) plaques and neurofibrillary tangles (NFT) comprising hyperphosphorylated tau (pTau) protein, have long been described in the brain, identification of these characteristic biomarkers in the retina has only recently been reported. In particular, Aβ deposits were discovered in post-mortem retinas of advanced and early stage cases of AD, in stark contrast to non-AD controls. Subsequent studies have reported elevated Aβ42/40 peptides, morphologically diverse Aβ plaques, and pTau in the retina. In line with the above findings, animal model studies have reported retinal Aβ deposits and tauopathy, often correlated with local inflammation, retinal ganglion cell degeneration, and functional deficits. This review highlights the converging evidence that AD manifests in the eye, especially in the retina, which can be imaged directly and non-invasively. Visual dysfunction in AD patients, traditionally attributed to well-documented cerebral pathology, can now be reexamined as a direct outcome of retinal abnormalities. As we continue to study the disease in the brain, the emerging field of ocular AD warrants further investigation of how the retina may faithfully reflect the neurological disease. Indeed, detection of retinal AD pathology, particularly the early presenting amyloid biomarkers, using advanced high-resolution imaging techniques may allow large-scale screening and monitoring of at-risk populations.
Collapse
Affiliation(s)
- Nadav J Hart
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Research Institute, Cedars-Sinai Medical Center, 127 S. San Vicente Blvd., Los Angeles, 90048, CA, USA
| | - Yosef Koronyo
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Research Institute, Cedars-Sinai Medical Center, 127 S. San Vicente Blvd., Los Angeles, 90048, CA, USA
| | - Keith L Black
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Research Institute, Cedars-Sinai Medical Center, 127 S. San Vicente Blvd., Los Angeles, 90048, CA, USA
| | - Maya Koronyo-Hamaoui
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Research Institute, Cedars-Sinai Medical Center, 127 S. San Vicente Blvd., Los Angeles, 90048, CA, USA.
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, 110 George Burns Rd., Los Angeles, CA, 90048, USA.
| |
Collapse
|
59
|
The phasor-FLIM fingerprints reveal shifts from OXPHOS to enhanced glycolysis in Huntington Disease. Sci Rep 2016; 6:34755. [PMID: 27713486 PMCID: PMC5054433 DOI: 10.1038/srep34755] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 09/15/2016] [Indexed: 01/21/2023] Open
Abstract
Huntington disease (HD) is an autosomal neurodegenerative disorder caused by the expansion of Polyglutamine (polyQ) in exon 1 of the Huntingtin protein. Glutamine repeats below 36 are considered normal while repeats above 40 lead to HD. Impairment in energy metabolism is a common trend in Huntington pathogenesis; however, this effect is not fully understood. Here, we used the phasor approach and Fluorescence Lifetime Imaging Microscopy (FLIM) to measure changes between free and bound fractions of NADH as a indirect measure of metabolic alteration in living cells. Using Phasor-FLIM, pixel maps of metabolic alteration in HEK293 cell lines and in transgenic Drosophila expressing expanded and unexpanded polyQ HTT exon1 in the eye disc were developed. We found a significant shift towards increased free NADH, indicating an increased glycolytic state for cells and tissues expressing the expanded polyQ compared to unexpanded control. In the nucleus, a further lifetime shift occurs towards higher free NADH suggesting a possible synergism between metabolic dysfunction and transcriptional regulation. Our results indicate that metabolic dysfunction in HD shifts to increased glycolysis leading to oxidative stress and cell death. This powerful label free method can be used to screen native HD tissue samples and for potential drug screening.
Collapse
|
60
|
Klemm M, Blum J, Link D, Hammer M, Haueisen J, Schweitzer D. Combination of confocal principle and aperture stop separation improves suppression of crystalline lens fluorescence in an eye model. BIOMEDICAL OPTICS EXPRESS 2016; 7:3198-3210. [PMID: 27699092 PMCID: PMC5030004 DOI: 10.1364/boe.7.003198] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 07/11/2016] [Accepted: 07/11/2016] [Indexed: 05/21/2023]
Abstract
Fluorescence lifetime imaging ophthalmoscopy (FLIO) is a new technique to detect changes in the human retina. The autofluorescence decay over time, generated by endogenous fluorophores, is measured in vivo. The strong autofluorescence of the crystalline lens, however, superimposes the intensity decay of the retina fluorescence, as the confocal principle is not able to suppress it sufficiently. Thus, the crystalline lens autofluorescence causes artifacts in the retinal fluorescence lifetimes determined from the intensity decays. Here, we present a new technique to suppress the autofluorescence of the crystalline lens by introducing an annular stop into the detection light path, which we call Schweitzer's principle. The efficacy of annular stops with an outer diameter of 7 mm and inner diameters of 1 to 5 mm are analyzed in an experimental setup using a model eye based on fluorescent dyes. Compared to the confocal principle, Schweitzer's principle with an inner diameter of 3 mm is able to reduce the simulated crystalline lens fluorescence to 4%, while 42% of the simulated retina fluorescence is preserved. Thus, we recommend the implementation of Schweitzer's principle in scanning laser ophthalmoscopes used for fundus autofluorescence measurements, especially the FLIO device, for improved image quality.
Collapse
Affiliation(s)
- Matthias Klemm
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, POB 100565, 98694 Ilmenau, Germany
| | - Johannes Blum
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, POB 100565, 98694 Ilmenau, Germany
| | - Dietmar Link
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, POB 100565, 98694 Ilmenau, Germany
| | - Martin Hammer
- Experimental Ophthalmology, University Hospital Jena, Bachstraße 18, 07740 Jena, Germany
| | - Jens Haueisen
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, POB 100565, 98694 Ilmenau, Germany
| | - Dietrich Schweitzer
- Experimental Ophthalmology, University Hospital Jena, Bachstraße 18, 07740 Jena, Germany
| |
Collapse
|
61
|
Garcia-Martin E, Bambo MP, Marques ML, Satue M, Otin S, Larrosa JM, Polo V, Pablo LE. Ganglion cell layer measurements correlate with disease severity in patients with Alzheimer's disease. Acta Ophthalmol 2016; 94:e454-9. [PMID: 26895692 DOI: 10.1111/aos.12977] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 11/29/2015] [Indexed: 01/03/2023]
Abstract
PURPOSE To evaluate the thickness of the 10 retinal layers of patients with Alzheimer's disease (AD) using a new segmentation technology of the Spectralis optical coherence tomography (OCT) and to determine whether the thickness of specific layers predicts neurodegeneration or AD severity. METHODS Patients with AD (n = 150) and age-matched healthy controls (n = 75) were analysed using the segmentation application prototype to automatically segment all retinal layers in a macular scan. Thicknesses of each layer were compared between patients with AD and controls, and between patients with disease durations of less than or at least 3 years. Associations between retinal layer thicknesses, disease duration and AD severity were evaluated. RESULTS Patients with AD had reduced thickness in the retinal nerve fibre, ganglion cell, inner plexiform and outer nuclear layers (p < 0.05). The inner retinal layers were more affected in patients with long disease duration. Ganglion cell and retinal nerve fibre layer thicknesses were inversely correlated with AD duration and severity. Ganglion cell and inner plexiform layers thicknesses were predictive of axonal damage. CONCLUSIONS The segmentation application revealed ganglion cell and retinal layer atrophy in patients with AD compared with controls, especially in the inner layers of patients with long disease duration. Ganglion cell layer reduction was associated with increased axonal damage and may predict greater disease severity.
Collapse
Affiliation(s)
- Elena Garcia-Martin
- Ophthalmology Department; Miguel Servet University Hospital; Zaragoza Spain
- Aragon Institute of Health Research; IIS-Aragon; Zaragoza Spain
| | - Maria P. Bambo
- Ophthalmology Department; Miguel Servet University Hospital; Zaragoza Spain
- Aragon Institute of Health Research; IIS-Aragon; Zaragoza Spain
| | | | - Maria Satue
- Ophthalmology Department; Miguel Servet University Hospital; Zaragoza Spain
- Aragon Institute of Health Research; IIS-Aragon; Zaragoza Spain
| | - Sofia Otin
- Ophthalmology Department; Miguel Servet University Hospital; Zaragoza Spain
- Aragon Institute of Health Research; IIS-Aragon; Zaragoza Spain
| | - Jose M. Larrosa
- Ophthalmology Department; Miguel Servet University Hospital; Zaragoza Spain
- Aragon Institute of Health Research; IIS-Aragon; Zaragoza Spain
| | - Vicente Polo
- Ophthalmology Department; Miguel Servet University Hospital; Zaragoza Spain
- Aragon Institute of Health Research; IIS-Aragon; Zaragoza Spain
| | - Luis E. Pablo
- Aragon Institute of Health Research; IIS-Aragon; Zaragoza Spain
| |
Collapse
|
62
|
Javaid FZ, Brenton J, Guo L, Cordeiro MF. Visual and Ocular Manifestations of Alzheimer's Disease and Their Use as Biomarkers for Diagnosis and Progression. Front Neurol 2016; 7:55. [PMID: 27148157 PMCID: PMC4836138 DOI: 10.3389/fneur.2016.00055] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 03/29/2016] [Indexed: 12/21/2022] Open
Abstract
Alzheimer's disease (AD) is the most common form of dementia affecting the growing aging population today, with prevalence expected to rise over the next 35 years. Clinically, patients exhibit a progressive decline in cognition, memory, and social functioning due to deposition of amyloid β (Aβ) protein and intracellular hyperphosphorylated tau protein. These pathological hallmarks of AD are measured either through neuroimaging, cerebrospinal fluid analysis, or diagnosed post-mortem. Importantly, neuropathological progression occurs in the eye as well as the brain, and multiple visual changes have been noted in both human and animal models of AD. The eye offers itself as a transparent medium to cerebral pathology and has thus potentiated the development of ocular biomarkers for AD. The use of non-invasive screening, such as retinal imaging and visual testing, may enable earlier diagnosis in the clinical setting, minimizing invasive and expensive investigations. It also potentially improves disease management and quality of life for AD patients, as an earlier diagnosis allows initiation of medication and treatment. In this review, we explore the evidence surrounding ocular changes in AD and consider the biomarkers currently in development for early diagnosis.
Collapse
Affiliation(s)
- Fatimah Zara Javaid
- Glaucoma and Retinal Degeneration Research Group, Visual Neurosciences, UCL Institute of Ophthalmology, London, UK
| | - Jonathan Brenton
- Glaucoma and Retinal Degeneration Research Group, Visual Neurosciences, UCL Institute of Ophthalmology, London, UK
| | - Li Guo
- Glaucoma and Retinal Degeneration Research Group, Visual Neurosciences, UCL Institute of Ophthalmology, London, UK
| | - Maria F. Cordeiro
- Glaucoma and Retinal Degeneration Research Group, Visual Neurosciences, UCL Institute of Ophthalmology, London, UK
- Western Eye Hospital, Imperial College Healthcare NHS Trust, London, UK
| |
Collapse
|
63
|
Madeira MH, Ambrósio AF, Santiago AR. Glia-Mediated Retinal Neuroinflammation as a Biomarker in Alzheimer's Disease. Ophthalmic Res 2015; 54:204-11. [PMID: 26517861 DOI: 10.1159/000440887] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 09/06/2015] [Indexed: 11/19/2022]
Abstract
Alzheimer's disease (AD) is the most common type of dementia worldwide; it is characterized by a progressive decline in cognitive functions and memory, resulting from synaptic and cell loss, and accompanied by a strong neuroinflammatory response. Besides the vast progress in the understanding of the pathophysiology of AD in the past decades, there is still no effective treatment. Moreover, the diagnosis occurs usually at an advanced stage of the disease, where the neurological damage has already occurred. The identification of biomarkers that would allow an early diagnosis of this disease is a major goal that would also help managing AD progression. Due to its cellular and physiological resemblances with the brain, the retina has long been regarded as a window to the brain. Several brain manifestations have been associated with retinal alterations. In AD patients, some structural and functional alterations in the retina can be associated with disease onset. However, only a few studies have focused on the alterations in retinal glial cells associated with AD. This review aims at giving an overview of the AD-associated retinal alterations, particularly in glial cells. The documented alterations in retinal glia will be discussed concerning their potential to predict the brain alterations occurring in AD.
Collapse
Affiliation(s)
- Maria Helena Madeira
- Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | | | | |
Collapse
|
64
|
Klemm M, Schweitzer D, Peters S, Sauer L, Hammer M, Haueisen J. FLIMX: A Software Package to Determine and Analyze the Fluorescence Lifetime in Time-Resolved Fluorescence Data from the Human Eye. PLoS One 2015; 10:e0131640. [PMID: 26192624 PMCID: PMC4507995 DOI: 10.1371/journal.pone.0131640] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 06/04/2015] [Indexed: 02/02/2023] Open
Abstract
Fluorescence lifetime imaging ophthalmoscopy (FLIO) is a new technique for measuring the in vivo autofluorescence intensity decays generated by endogenous fluorophores in the ocular fundus. Here, we present a software package called FLIM eXplorer (FLIMX) for analyzing FLIO data. Specifically, we introduce a new adaptive binning approach as an optimal tradeoff between the spatial resolution and the number of photons required per pixel. We also expand existing decay models (multi-exponential, stretched exponential, spectral global analysis, incomplete decay) to account for the layered structure of the eye and present a method to correct for the influence of the crystalline lens fluorescence on the retina fluorescence. Subsequently, the Holm-Bonferroni method is applied to FLIO measurements to allow for group comparisons between patients and controls on the basis of fluorescence lifetime parameters. The performance of the new approaches was evaluated in five experiments. Specifically, we evaluated static and adaptive binning in a diabetes mellitus patient, we compared the different decay models in a healthy volunteer and performed a group comparison between diabetes patients and controls. An overview of the visualization capabilities and a comparison of static and adaptive binning is shown for a patient with macular hole. FLIMX’s applicability to fluorescence lifetime imaging microscopy is shown in the ganglion cell layer of a porcine retina sample, obtained by a laser scanning microscope using two-photon excitation.
Collapse
Affiliation(s)
- Matthias Klemm
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, POB 100565, 98694, Ilmenau, Germany
- * E-mail:
| | - Dietrich Schweitzer
- Experimental Ophthalmology, University Hospital Jena, Bachstraße 18, 07740, Jena, Germany
| | - Sven Peters
- Experimental Ophthalmology, University Hospital Jena, Bachstraße 18, 07740, Jena, Germany
| | - Lydia Sauer
- Experimental Ophthalmology, University Hospital Jena, Bachstraße 18, 07740, Jena, Germany
| | - Martin Hammer
- Experimental Ophthalmology, University Hospital Jena, Bachstraße 18, 07740, Jena, Germany
| | - Jens Haueisen
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, POB 100565, 98694, Ilmenau, Germany
| |
Collapse
|