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Wong KY, Liu Y, Zhou L, Wong MS, Liu J. Mucin-targeting-aptamer functionalized liposomes for delivery of cyclosporin A for dry eye diseases. J Mater Chem B 2023; 11:4684-4694. [PMID: 37161679 DOI: 10.1039/d3tb00598d] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Traditional eye drops are convenient to use; however, their effectiveness is limited by their poor retention time and bioavailability in the eyes due to ocular barriers. Therefore, strategies to enhance ocular drug delivery are required. Herein, we constructed a mucin-1 aptamer-functionalized liposome and loaded it with cyclosporin A, a common ocular drug in eye drops used to treat dry eye diseases (DED). Drug encapsulation slightly reduced the liposome size without changing the surface potential of liposomes. Approximately 90% of the cholesterol-modified aptamers were inserted to the liposomes. We evaluated the cytotoxicity, anti-inflammatory effects, cell permeability regulation, and retention time of liposomes in human corneal epithelial cells under dry eye conditions. These results suggest that the aptamer-functionalized liposomes are more efficient as nanocarriers than non-functionalized liposomes and drug-free liposomes. They restore inflammation levels by 1-fold and remain in the cells for up to 24 h. An in vivo study was also performed in a rat DED model, which demonstrated the efficacy of aptamer-functionalized liposomes in restoring tear production and corneal integrity. The present study demonstrated the capability of aptamer-functionalized liposomes in the delivery of ocular drugs for the management of ocular diseases.
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Affiliation(s)
- Ka-Ying Wong
- Centre for Eye and Vision Research (CEVR), 17W Hong Kong, Science Park, Hong Kong.
- Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Yibo Liu
- Centre for Eye and Vision Research (CEVR), 17W Hong Kong, Science Park, Hong Kong.
- Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Liping Zhou
- Centre for Eye and Vision Research (CEVR), 17W Hong Kong, Science Park, Hong Kong.
- Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, P. R. China
- Research Center for Chinese Medicine Innovation, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, P. R. China
- School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, P. R. China
| | - Man-Sau Wong
- Centre for Eye and Vision Research (CEVR), 17W Hong Kong, Science Park, Hong Kong.
- Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, P. R. China
- Research Center for Chinese Medicine Innovation, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, P. R. China
| | - Juewen Liu
- Centre for Eye and Vision Research (CEVR), 17W Hong Kong, Science Park, Hong Kong.
- Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
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Chintala SK, Pan J, Satapathy S, Condruti R, Hao Z, Liu PW, O’Conner CF, Barr JT, Wilson MR, Jeong S, Fini ME. Recombinant Human Clusterin Seals Damage to the Ocular Surface Barrier in a Mouse Model of Ophthalmic Preservative-Induced Epitheliopathy. Int J Mol Sci 2023; 24:ijms24020981. [PMID: 36674497 PMCID: PMC9861099 DOI: 10.3390/ijms24020981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/23/2022] [Accepted: 12/31/2022] [Indexed: 01/07/2023] Open
Abstract
There is a significant unmet need for therapeutics to treat ocular surface barrier damage, also called epitheliopathy, due to dry eye and related diseases. We recently reported that the natural tear glycoprotein CLU (clusterin), a molecular chaperone and matrix metalloproteinase inhibitor, seals and heals epitheliopathy in mice subjected to desiccating stress in a model of aqueous-deficient/evaporative dry eye. Here we investigated CLU sealing using a second model with features of ophthalmic preservative-induced dry eye. The ocular surface was stressed by topical application of the ophthalmic preservative benzalkonium chloride (BAC). Then eyes were treated with CLU and sealing was evaluated immediately by quantification of clinical dye uptake. A commercial recombinant form of human CLU (rhCLU), as well as an rhCLU form produced in our laboratory, designed to be compatible with U.S. Food and Drug Administration guidelines on current Good Manufacturing Practices (cGMP), were as effective as natural plasma-derived human CLU (pCLU) in sealing the damaged ocular surface barrier. In contrast, two other proteins found in tears: TIMP1 and LCN1 (tear lipocalin), exhibited no sealing activity. The efficacy and selectivity of rhCLU for sealing of the damaged ocular surface epithelial barrier suggests that it could be of therapeutic value in treating BAC-induced epitheliopathy and related diseases.
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Affiliation(s)
- Shravan K. Chintala
- USC Institute for Genetic Medicine, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA 90033, USA
| | - Jinhong Pan
- New England Eye Center, Tufts Medical Center, Department of Ophthalmology, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Sandeep Satapathy
- School of Chemistry and Molecular Bioscience, Molecular Horizons Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Rebecca Condruti
- Training Program in Cell, Molecular and Developmental Biology, Graduate School of Biomedical Sciences, Tufts University, Boston, MA 02111, USA
| | - Zixuan Hao
- Training Program in Pharmacology and Drug Development, Graduate School of Biomedical Sciences, Tufts University, Boston, MA 02111, USA
| | - Pei-wen Liu
- Training Program in Pharmacology and Drug Development, Graduate School of Biomedical Sciences, Tufts University, Boston, MA 02111, USA
| | - Christian F. O’Conner
- Doctor of Medicine Training Program, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Joseph T. Barr
- The Ohio State University College of Optometry, Columbus, OH 43210, USA
| | - Mark R. Wilson
- School of Chemistry and Molecular Bioscience, Molecular Horizons Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Shinwu Jeong
- USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA 90033, USA
| | - M. Elizabeth Fini
- New England Eye Center, Tufts Medical Center, Department of Ophthalmology, Tufts University School of Medicine, Boston, MA 02111, USA
- Correspondence:
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Iwashita H, Sebbag L, Leonard BC, Saito A. A review of diagnostic tests for qualitative and quantitative tear film deficiency in dogs. Vet Ophthalmol 2022; 26 Suppl 1:5-15. [PMID: 36575128 DOI: 10.1111/vop.13044] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 11/22/2022] [Indexed: 12/29/2022]
Abstract
Dry eye disease (DED) is a complex multifactorial condition caused by loss of ocular surface homeostasis from quantitative and/or qualitative tear film deficiency. Schirmer tear test (STT) is often the only diagnostic test used to assess for DED in veterinary practice. STT is invaluable in the diagnosis and monitoring of quantitative tear film deficiency (i.e., keratoconjunctivitis sicca); however, it is not sufficient to optimize therapy and fully recognize other contributing factors for the disturbance in ocular surface homeostasis. The present work reviews diagnostic tests for assessing aqueous tear production in veterinary medicine, as well as the quality of tears, corneal epithelial barrier integrity, and the lacrimal functional unit.
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Affiliation(s)
| | - Lionel Sebbag
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Brian C Leonard
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, California, USA
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Begley CG, Caffery B, Nelson JD, Situ P. The effect of time on grading corneal fluorescein and conjunctival lissamine green staining. Ocul Surf 2022; 25:65-70. [PMID: 35568371 DOI: 10.1016/j.jtos.2022.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/04/2022] [Accepted: 05/07/2022] [Indexed: 11/25/2022]
Abstract
PURPOSE To explore the effect of time on grading corneal fluorescein and conjunctival lissamine green staining in dry eye disease (DED). METHODS Photographs of 68 subjects with non-Sjogren's DED (nSS DED) and 32 with Sjogren's DED (SS DED) were taken of corneal fluorescein staining, then conjunctival lissamine green staining every 30 s for at least 5 min. Photographs of one randomly selected eye were then randomly ordered and graded on a scale from 0 to 5 (severe staining) by two clinicians, masked to both site and subject. The average time required to reach the maximum grade of staining (Gmax) was calculated. RESULTS The median time (upper and lower quartiles) to corneal fluorescein Gmax was 2.6 (1.3-5.3) minutes for nSS DED and 3.8 (2.6-5.4) minutes for SS DED, a statistically significant difference (Mann Whitney U test, p = 0.018). In contrast, the median time to the Gmax for lissamine green staining of the nasal and temporal conjunctiva was 0.5 (0.5-1.1 nasal, 0.5-0.8 temporal) minutes for nSS DED and 0.5 (0.5-0.8 nasal, 0.5-0.5 temporal) minutes for SS DED subjects, which was not statistically significant (p ≥ 0.383). CONCLUSIONS The time required to reach the maximum grade of corneal fluorescein staining, but not conjunctival lissamine green staining, varied widely and was significantly longer in subjects with Sjögren's Syndrome. Early observation of corneal fluorescein staining can lead to under-grading, which may impact the diagnosis and assessment of treatment in DED. Further study of the best time to assess corneal fluorescein staining in various DED populations is warranted.
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Affiliation(s)
| | | | | | - Ping Situ
- Indiana University School of Optometry, Bloomington, IN, USA
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5
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Sun YC, Hung KF, Li TY, Chang YA, Yeh PT, Hu FR. Transmembrane Mucin 1 Blocks Fluorescein Ingress to Corneal Epithelium. Invest Ophthalmol Vis Sci 2022; 63:31. [PMID: 35212722 PMCID: PMC8883176 DOI: 10.1167/iovs.63.2.31] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Purpose To determine the role of transmembrane mucins in blocking fluorescein ingress to the corneal epithelium and its deficiency in contributing to corneal fluorescein punctate staining. Methods A dry eye model was established by extirpating lacrimal and Harderian glands in rabbits to correlate the expression of mucins with fluorescein-stained areas on the corneal button using immunofluorescence. Expression of transmembrane mucins was promoted in human corneal epithelial cells (HCECs) by culturing with the mucin-promoting medium (MPM) or diquafosol treatment. Conversely, the expression of mucins was downregulated by knockdown with short hairpin RNA. The role of mucin1 extracellular domain in fluorescein ingress was further verified by overexpression of N-terminally truncated mucin1 in HCECs. Results In the rabbit dry eye model, the expression level of mucin1 was significantly decreased in superficial corneal epithelial cells where fluorescein punctate staining was observed. Upregulation of mucin1 and mucin16 in HCECs promoted by MPM or by diquafosol treatment impeded intracellular fluorescein ingress. Downregulation of mucin1 and mucin16 enhanced fluorescence ingress in HCECs after fluorescein staining. Overexpression of truncated mucin1 did not alter the fluorescein intensity of fluorescein-stained HCECs, supporting the notion that the ability of mucin1 to block fluorescein ingress was primarily mediated by its extracellular domain. Minimal inherent expression of mucin16 in the rabbit cornea limited the validation of its role in blocking fluorescein ingress in vivo. Conclusion Transmembrane mucin1 blocks fluorescein ingress in the corneal epithelium, explaining how fluorescein staining is positive when the level of transmembrane mucins is disturbed in dry eyes.
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Affiliation(s)
- Yi-Chen Sun
- Department of Ophthalmology, Taipei Tzu Chi Hospital, The Buddhist Tzu Chi Medical Foundation, New Taipei City, Taiwan.,College of Medicine, Tzu-Chi University, Hualien, Taiwan
| | - Kai-Feng Hung
- Department of Medical Research, Division of Translational Research, Taipei Veterans General Hospital, Taipei, Taiwan, ROC.,Department of Dentistry, School of Dentistry, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC
| | - Tzu-Yun Li
- Department of Ophthalmology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yu-An Chang
- Graduate Institute of Veterinary Clinical Science, School of Veterinary Medicine, National Taiwan University, Taipei, Taiwan
| | - Po-Ting Yeh
- Department of Ophthalmology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Fung-Rong Hu
- Department of Ophthalmology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan
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An Evaluation of a Simplified Impression Membrane Sampling Method for the Diagnosis of Microbial Keratitis. J Clin Med 2021; 10:jcm10235671. [PMID: 34884373 PMCID: PMC8658700 DOI: 10.3390/jcm10235671] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 11/25/2021] [Accepted: 11/29/2021] [Indexed: 12/12/2022] Open
Abstract
The purpose of this study was to compare bacterial isolation rate using a corneal impression membrane (CIM) and a sharp instrument for obtaining corneal samples from patients with suspected microbial keratitis (MK). Data was retrospectively collected for all patients that had corneal samples taken for presumed MK between May 2014 and May 2020. Prior to May 2017 samples were collected by scraping the edges of the ulcer with a blade. From May 2017, samples were collected by placing a CIM (Millicell cell culture insert) against the ulcer. All corneal samples were processed using the same conventional diagnostic culture method. A total of 3099 corneal samples were included, of which 1214 (39.2%) were corneal scrapes and 1885 (60.9%) CIMs. Microorganisms were isolated from 235 (19.4%) and 1229 (65.2%) cases using a corneal scrape and CIM, respectively (p < 0.001). Of routinely described pathogenic microorganisms, there were significant increases in the isolations of S. aureus (2.4% to 11.3%) and Serratia (0.5% to 1.7%) using the CIM and no significant changes in the isolations of S. pneumoniae and P. aeruginosa. No significant differences were seen between the isolation rates of fungi or Acanthamoeba species. There was a significant increase in the isolation rates of other Streptococcal species (0.7% to 6.9%) and CNS species, specifically, S. epidermidis (2.1% to 26.2%), S. capitis (0.4% to 2.6%) and S. warneri (0.3% to 1.6%) using the CIM. The simplified CIM sampling method is an effective method for collecting corneal samples from patients with presumed MK in clinical practice.
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Martinez-Carrasco R, Argüeso P, Fini ME. Membrane-associated mucins of the human ocular surface in health and disease. Ocul Surf 2021; 21:313-330. [PMID: 33775913 PMCID: PMC8328898 DOI: 10.1016/j.jtos.2021.03.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 03/02/2021] [Accepted: 03/08/2021] [Indexed: 02/06/2023]
Abstract
Mucins are a family of high molecular weight, heavily-glycosylated proteins produced by wet epithelial tissues, including the ocular surface epithelia. Densely-packed O-linked glycan chains added post-translationally confer the biophysical properties of hydration, lubrication, anti-adhesion and repulsion. Membrane-associated mucins (MAMs) are the distinguishing components of the mucosal glycocalyx. At the ocular surface, MAMs maintain wetness, lubricate the blink, stabilize the tear film, and create a physical barrier to the outside world. In addition, it is increasingly appreciated that MAMs function as cell surface receptors that transduce information from the outside to the inside of the cell. Recently, our team published a comprehensive review/perspectives article for molecular scientists on ocular surface MAMs, including previously unpublished data and analyses on two new genes MUC21 and MUC22, as well as new MAM functions and biological roles, comparing human and mouse (PMID: 31493487). The current article is a refocus for the audience of The Ocular Surface. First, we update the gene and protein information in a more concise form, and include a new section on glycosylation. Next, we discuss biological roles, with some new sections and further updating from our previous review. Finally, we provide a new chapter on MAM involvement in ocular surface disease. We end this with discussion of an emerging mechanism responsible for damage to the epithelia and their mucosal glycocalyces: the unfolded protein response (UPR). The UPR offers a novel target for therapeutic intervention.
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Affiliation(s)
- Rafael Martinez-Carrasco
- Department of Ophthalmology, Tufts University School of Medicine at New England Eye Center, Tufts Medical Center, Boston, MA, 02111, USA.
| | - Pablo Argüeso
- Department of Ophthalmology, Harvard Medical School at Schepens Eye Research Institute of Mass, Eye and Ear, Boston, MA, 02114, USA.
| | - M Elizabeth Fini
- Department of Ophthalmology, Tufts University School of Medicine at New England Eye Center, Tufts Medical Center: Program in Pharmacology & Drug Development, Graduate School of Biomedical Sciences, Tufts University, Boston, MA, O2111, USA.
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Abstract
Purpose The structure of tears has been theoretically considered three tiers with lipids at the air interface, aqueous and proteins in the subphase, and anchored mucins on the corneal epithelial surface. While many lipid and protein species have been identified in tears by mass spectrometry, the localization of the major components within the tear film structure remains speculative. The most controversial components are phospholipids. Although surface active, phospholipids have been presumed to be bound entirely to protein in the aqueous portion of tears or reside at the aqueous-lipid interface. Herein, the possibility that phospholipids are adsorbed at the air-surface interface of tears is interrogated. Methods Polarization-modulated Fourier transform infrared reflective absorption spectroscopy (PM-IRRAS) was used to study the presence of phosphate signals at the tear surface. In order to constrain the depth of signal detection to the surface, an extreme grazing angle of incident radiation was employed. Nulling ellipsometry was used to confirm the presence of monolayers and surface thicknesses when surface active reagents were added to solutions. Results Surface selection of PM-IRRAS was demonstrated by suppression of water and phosphate signals in buffers with monolayers of oleic acid. Phosphate signals were shown to reflect relative concentrations. Absorption peaks attributable to phospholipids were detected by PM-IRRAS on the human tear film surface and were augmented by the addition of phospholipid. Conclusions The data provide strong evidence that phospholipids are present at the surface of tears.
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Affiliation(s)
- Ben J Glasgow
- Departments of Pathology and Ophthalmology, UCLA School of Medicine, Jules Stein Eye Institute, Los Angeles, California, United States
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9
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Efron N. Putting vital stains in context. Clin Exp Optom 2021; 96:400-21. [DOI: 10.1111/j.1444-0938.2012.00802.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 06/17/2012] [Accepted: 06/19/2012] [Indexed: 11/30/2022] Open
Affiliation(s)
- Nathan Efron
- Institute of Health and Biomedical Innovation, and School of Optometry and Vision Science, Queensland University of Technology, Kelvin Grove, Queensland, Australia,
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10
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Glasgow BJ, Abduragimov AR. Lipocalin-1 is the acceptor protein for phospholipid transfer protein in tears. Biochem Biophys Res Commun 2021; 548:35-38. [PMID: 33631671 DOI: 10.1016/j.bbrc.2021.02.054] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 02/12/2021] [Indexed: 12/12/2022]
Abstract
Phospholipid transfer protein, ∼80 kDa, transfers phospholipids from micelles to lipid binding proteins. The acceptor protein in plasma is apolipoprotein-A1, 28 kDa. Previously, phospholipid transfer protein was found in tears but an acceptor protein was not identified. To search for the acceptor protein(s) in tears a fluorescent phospholipid transfer assay was altered to omit the extrinsic acceptor. Human tears were incubated with fluorescent micelles and showed marked transfer activity verifying a native acceptor protein must be present. Reconstituted tears without tear lipocalin (lipocalin-1) eliminated the transfer of phospholipids. To determine if phospholipid transfer protein is involved in carrying phospholipid to the surface of tears from tear lipocalin, a fraction enriched in phospholipid transfer protein was injected into the subphase of a tear mimicking buffer in which tear lipocalin was present. The addition of phospholipid transfer protein did not increase the thickness of the surface layer regardless of the presence of lipid bearing tear lipocalin. The data show that phospholipid transfer protein transfers phospholipid from micelles to tear lipocalin. Phospholipid transfer protein does not transport the phospholipid. While tear lipocalin has no intrinsic transfer activity from micelles, it is the acceptor protein for phospholipid transfer protein in tears.
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Affiliation(s)
- Ben J Glasgow
- Departments of Ophthalmology, Pathology and Laboratory Medicine, Jules Stein Eye Institute, 100 Stein Plaza, University of California, Los Angeles, CA, 90095, USA.
| | - Adil R Abduragimov
- Departments of Ophthalmology, Pathology and Laboratory Medicine, Jules Stein Eye Institute, 100 Stein Plaza, University of California, Los Angeles, CA, 90095, USA.
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11
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Dongre PM, Jaiswal VD, Singh S. Effect of Smartphone Light Fluxes on Cornea: A Biophysical Study. J Med Phys 2021; 45:187-194. [PMID: 33487932 PMCID: PMC7810147 DOI: 10.4103/jmp.jmp_89_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 07/09/2020] [Accepted: 08/06/2020] [Indexed: 11/04/2022] Open
Abstract
Objective Biophysical study to investigate (a) the effects of smartphone light fluxes (SPLF) on isolated mammalian cornea and model protein (insulin), (b) to predict the possible visual interference of SPLF. Materials and Methods Fresh goat cornea and insulin protein were used as an experimental model system. The energy of absorbed SPLF was measured using chemical dosimeter. The effect of SPLF on the aggregation of model protein was studied using fluorescence spectroscopy and dynamic light scattering (DLS). Fluorescence microscopy, scanning electron microscopy (SEM), DLS, were used for cornea imaging. Results The spectral emission peak of SPLF was observed at 380 nm and 420 nm. Absorbed radiation of SPLF was found to be 2.82 mWm-2 and 1.92 mWm-2 for collimated (focussed) and noncollimated (nonfocussed) condition, respectively. Secondary structural changes of insulin were observed by fluorescence and zeta potential after SPLF exposure. SEM study revealed the disorganization of the epithelial cell surface, increase in intercellular space, disorganization of primary epithelium layer, and exposure of the second layer is seen in depth. Differential Interference Microscopy showed an optical gradient in images that appears to be changed in specimen structure. Fluorescence microscopy showed disorganization in epithelial cell pattern. A significant difference in bio-molecular permeation was observed in the exposed cornea. Ultraviolet UV-visible spectroscopy study indicated a reduction in light transmission through the cornea. Conclusions The obtained results indicate changes in physicochemical and morphological modifications in the cornea and insulin modifications after exposed to SPLF.
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Affiliation(s)
- P M Dongre
- Department of Biophysics, University of Mumbai, Mumbai, Maharashtra, India
| | - Vinod D Jaiswal
- Department of Biophysics, University of Mumbai, Mumbai, Maharashtra, India
| | - Suraj Singh
- Department of Biophysics, University of Mumbai, Mumbai, Maharashtra, India
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12
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Fini ME, Jeong S, Wilson MR. Therapeutic Potential of the Molecular Chaperone and Matrix Metalloproteinase Inhibitor Clusterin for Dry Eye. Int J Mol Sci 2020; 22:E116. [PMID: 33374364 PMCID: PMC7794831 DOI: 10.3390/ijms22010116] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 12/19/2020] [Accepted: 12/21/2020] [Indexed: 12/29/2022] Open
Abstract
Evidence is presented herein supporting the potential of the natural homeostatic glycoprotein CLU (clusterin) as a novel therapeutic for the treatment of dry eye. This idea began with the demonstration that matrix metalloproteinase MMP9 is required for damage to the ocular surface in mouse dry eye. Damage was characterized by degradation of OCLN (occludin), a known substrate of MMP9 and a key component of the paracellular barrier. Following up on this finding, a yeast two-hybrid screen was conducted using MMP9 as the bait to identify other proteins involved. CLU emerged as a strong interacting protein that inhibits the enzymatic activity of MMP9. Previously characterized as a molecular chaperone, CLU is expressed prominently by epithelia at fluid-tissue interfaces and secreted into bodily fluids, where it protects cells and tissues against damaging stress. It was demonstrated that CLU also protects the ocular surface in mouse dry eye when applied topically to replace the natural protein depleted from the dysfunctional tears. CLU is similarly depleted from tears in human dry eye. The most novel and interesting finding was that CLU binds selectively to the damaged ocular surface. In this position, CLU protects against epithelial cell death and barrier proteolysis, and dampens the autoimmune response, while the apical epithelial cell layer is renewed. When present at high enough concentration, CLU also blocks staining by vital dyes used clinically to diagnose dry eye. None of the current therapeutics have this combination of properties to "protect, seal, and heal". Future work will be directed towards human clinical trials to investigate the therapeutic promise of CLU.
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Affiliation(s)
- M. Elizabeth Fini
- New England Eye Center, Tufts Medical Center and Department of Ophthalmology, Tufts University School of Medicine, Program in Pharmacology & Drug Development, Graduate School of Biomedical Sciences Tufts University, Boston, MA 02111, USA
| | - Shinwu Jeong
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA 90089, USA;
| | - Mark R. Wilson
- The Illawarra Health and Medical Research Institute, Molecular Horizons and the School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia;
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Messner A, Fischak C, Pfister M, Schützenberger K, Garreis F, Paulsen F, Stegmann H, Aranha dos Santos V, Garhöfer G, Schmetterer L, Werkmeister RM. Characterization of dry eye disease in a mouse model by optical coherence tomography and fluorescein staining. BIOMEDICAL OPTICS EXPRESS 2019; 10:4884-4895. [PMID: 31565532 PMCID: PMC6757454 DOI: 10.1364/boe.10.004884] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 07/31/2019] [Accepted: 08/01/2019] [Indexed: 06/10/2023]
Abstract
A custom-built ultrahigh-resolution optical coherence tomography (UHR-OCT) system and fluorescein staining were employed for investigation of a scopolamine induced dry eye mouse model. Acquired data was used to evaluate common and complementary findings of the two modalities. Central corneal thickness as measured by UHR-OCT increased significantly over the study period of 24 hours, from 89.0 ± 3.57 µm to 92.2 ± 4.07 µm. Both techniques were able to show corneal lesions with a large range of severity. Localized fluorescein staining was detected in 5% and diffuse staining in 45% of cases where no epithelial damage was visible with OCT. However, OCT revealed stromal defects in 6% and endothelial defects in 18% of the cases, which could not be visualized via fluorescein staining. Thus, while fluorescein staining widely detected defects of the corneal surface in a mouse model of dry eye disease, OCT non-invasively revealed additional information about defect depth and involvement of particular layers.
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Affiliation(s)
- Alina Messner
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Corinna Fischak
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
- Christian Doppler Laboratory for Ocular and Dermal Effects of Thiomers, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Martin Pfister
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
- Christian Doppler Laboratory for Ocular and Dermal Effects of Thiomers, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria
| | - Kornelia Schützenberger
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
- Christian Doppler Laboratory for Ocular and Dermal Effects of Thiomers, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Fabian Garreis
- Department of Functional and Clinical Anatomy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Friedrich Paulsen
- Department of Functional and Clinical Anatomy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Hannes Stegmann
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
- Christian Doppler Laboratory for Ocular and Dermal Effects of Thiomers, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Valentin Aranha dos Santos
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Leopold Schmetterer
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
- Christian Doppler Laboratory for Ocular and Dermal Effects of Thiomers, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
- Department of Clinical Pharmacology, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
- Singapore Eye Research Institute, The Academia, 20 College Road, Discovery Tower Level 6, 169856, Singapore
- Institute for Health Technologies, Nanyang Technological University, Singapore
- Academic Clinical Program, Duke-NUS Medical School, Singapore
| | - René M. Werkmeister
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
- Christian Doppler Laboratory for Ocular and Dermal Effects of Thiomers, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
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Pantalon A, Pfister M, Aranha dos Santos V, Sapeta S, Unterhuber A, Pircher N, Schmidinger G, Garhöfer G, Schmidl D, Schmetterer L, Werkmeister RM. Ultrahigh-resolution anterior segment optical coherence tomography for analysis of corneal microarchitecture during wound healing. Acta Ophthalmol 2019; 97:e761-e771. [PMID: 30762310 PMCID: PMC6767559 DOI: 10.1111/aos.14053] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 01/19/2019] [Indexed: 12/29/2022]
Abstract
PURPOSE To employ ultrahigh-resolution (UHR) optical coherence tomography (OCT) for investigation of the early wound healing process in corneal epithelium. METHODS A custom-built UHR-OCT system assessed epithelial healing in human keratoconic cornea after epi-off crosslinking (CXL) procedure and a wound healing model in rabbits with iatrogenic corneal injury. 3D OCT data sets enhanced obtaining epithelial thickness maps and evaluation of reepithelization stage. Accompanying changes in deeper corneal microarchitecture were analysed. RESULTS The mean central corneal thickness in 40 eyes with keratoconus at baseline was 482.7 ± 38.2 μm, while mean central epithelial thickness (CET) was 43.8 ± 6.4 μm. At the final visit 20 ± 5 days post-CXL procedure, CET was 35.0 ± 5.8 μm, significantly thinner after reepithelization (p < 0.001). Surgical success was assessed at the final visit through the demarcation line (DL), identified at 43.7 ± 13.5% stromal depth. In rabbits, the mean CET in 20 eyes at baseline was 35.9 ± 2.6 μm. In rabbits that revealed complete wound closure (10/20 eyes) at the last study day at 72 hr, CET was significantly thinner compared to baseline (30.4 ± 2.8 μm versus 35.4 ± 2.9 μm, p = 0.005). An intra-stromal landmark indicating early keratocyte apoptosis was measured at 30.0 ± 5.1% stromal depth. Epithelial thickness maps showed the time-course of corneal healing. CONCLUSION Ultrahigh-resolution (UHR)-OCT provided precise assessment of epithelial wound and its healing by 3D-mapping. In addition, microarchitectural changes in the cornea in early phases of epithelial healing were revealed.
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Affiliation(s)
- Anca Pantalon
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
- Department of OphthalmologyGr. T. Popa University of Medicine and PharmacyIasiRomania
| | - Martin Pfister
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
- Christian Doppler Laboratory for Ocular and Dermal Effects of ThiomersMedical University of ViennaViennaAustria
| | | | - Sabina Sapeta
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
| | - Angelika Unterhuber
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
| | - Niklas Pircher
- Department of OphthalmologyMedical University of ViennaViennaAustria
| | | | - Gerhard Garhöfer
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
| | - Doreen Schmidl
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
| | - Leopold Schmetterer
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
- Christian Doppler Laboratory for Ocular and Dermal Effects of ThiomersMedical University of ViennaViennaAustria
- Singapore Eye Research InstituteSingapore National Eye CentreSingaporeSingapore
- Ophthalmology and Visual Sciences Academic Clinical ProgramDuke‐NUS Medical SchoolSingaporeSingapore
- Ophthalmic Engineering & Innovation LaboratoryDepartment of Biomedical EngineeringFaculty of EngineeringNational University of SingaporeSingaporeSingapore
- Lee Kong Chian School of MedicineNanyang Technological UniversitySingaporeSingapore
| | - René M. Werkmeister
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
- Christian Doppler Laboratory for Ocular and Dermal Effects of ThiomersMedical University of ViennaViennaAustria
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15
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Ellipsometry of human tears. Ocul Surf 2019; 17:341-346. [PMID: 30818036 DOI: 10.1016/j.jtos.2019.02.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 01/12/2019] [Accepted: 02/20/2019] [Indexed: 12/17/2022]
Abstract
PURPOSE The outer surface layer of tears is presumably composed of lipid. The thickness of this layer is considered critical to retard evaporation. Prior thickness measurements differ widely. Advances in ellipsometry have availed more precise and accurate measurements for thin films. The range in thickness of the surface layer of tears was studied by ellipsometry to uncover the source of prior discrepancies. METHODS Tear surface layers of normal and dry eye subjects were measured by in-vitro ellipsometry. Lateral and Z resolutions of ∼1 μm and 0.1 nm, were achieved respectively. Thicknesses were derived from matrices and a Levenberg-Marquardt multivariate regression algorithm to Fresnel equations for multi-layered films. RESULTS Ellipsometric measurements of pooled and individual human tears in-vitro revealed a larger overall range (0-500 nm) of surface film thicknesses than previously reported by any one study. Each sample showed thin areas (0-2.6 nm) with interspersed thicker regions (∼200-500 nm). Repeat measurements of a single donor collected at weekly intervals showed a broad range of surface thicknesses within and between samples. Thickness measurements from a dry eye subject overlapped that of normal subjects. CONCLUSION The data show that published disparity in surface film thickness may be attributable to limitations of prior methodologies. The range and overlap of surface film thicknesses challenge less rigorous methodologies that claim to segregate normal and dry eye.
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Webster A, Chintala SK, Kim J, Ngan M, Itakura T, Panjwani N, Argüeso P, Barr JT, Jeong S, Fini ME. Dynasore protects the ocular surface against damaging oxidative stress. PLoS One 2018; 13:e0204288. [PMID: 30303976 PMCID: PMC6179211 DOI: 10.1371/journal.pone.0204288] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 09/04/2018] [Indexed: 02/04/2023] Open
Abstract
Water soluble "vital" dyes are commonly used clinically to evaluate health of the ocular surface; however, staining mechanisms remain poorly understood. Recent evidence suggests that sublethal damage stimulates vital dye uptake by individual living cells. Since cell damage can also stimulate reparative plasma membrane remodeling, we hypothesized that dye uptake occurs via endocytic vesicles. In support of this idea, we show here that application of oxidative stress to relatively undifferentiated monolayer cultures of human corneal epithelial cells stimulates both dye uptake and endocytosis, and that dye uptake is blocked by co-treatment with three different endocytosis inhibitors. Stress application to stratified and differentiated corneal epithelial cell cultures, which are a better model of the ocular surface, also stimulated dye uptake; however, endocytosis was not stimulated, and two of the endocytosis inhibitors did not block dye uptake. The exception was Dynasore and its more potent analogue Dyngo-4a, both small molecules developed to target dynamin family GTPases, but also having off-target effects on the plasma membrane. Significantly, while Dynasore blocked stress-stimulated dye uptake at the ocular surface of ex vivo mouse eyes when treatment was performed at the same time as eyes were stressed, it had no effect when used after stress was applied and the ocular surface was already damaged. Thus, Dynasore could not be working by inhibiting endocytosis. Employing cytotoxicity and western blotting assays, we went on to demonstrate an alternative mechanism. We show that Dynasore is remarkably protective of cells and their surface glycocalyx, preventing damage due to stress, and thus precluding dye entry. These unexpected and novel findings provide greater insight into the mechanisms of vital dye uptake and point the direction for future study. Significantly, they also suggest that Dynasore and its analogues might be used therapeutically to protect the ocular surface and to treat ocular surface disease.
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Affiliation(s)
- Andrew Webster
- USC Institute for Genetic Medicine, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States of America
| | - Shravan K. Chintala
- USC Institute for Genetic Medicine, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States of America
| | - Jasmine Kim
- Program in Biological Sciences, USC Dana and David Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, CA, United States of America
| | - Michelle Ngan
- Program in Preventive Medicine, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States of America
| | - Tatsuo Itakura
- USC Institute for Genetic Medicine, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States of America
| | - Noorjahan Panjwani
- New England Eye Center/Department of Ophthalmology and Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, United States of America
| | - Pablo Argüeso
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, United States of America
| | - Joseph T. Barr
- The Ohio State University College of Optometry, Columbus, OH, United States of America
| | - Shinwu Jeong
- USC Institute for Genetic Medicine and USC Roski Eye Institute/Department of Ophthalmology, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States of America
| | - M. Elizabeth Fini
- USC Institute for Genetic Medicine, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States of America
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17
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Somerville TF, Corless CE, Neal T, Kaye SB. Effect of storage time and temperature on the detection of Pseudomonas aeruginosa, Acanthamoeba and Herpes Simplex Virus from corneal impression membranes. J Med Microbiol 2018; 67:1321-1325. [PMID: 30051806 DOI: 10.1099/jmm.0.000812] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
The effect of storage time and temperature on the recovery of pathogen DNA from polytetrafluorethylene (PTFE) was investigated. PTFE impression membranes were inoculated with Pseudomonas aeruginosa, Herpes Simplex Virus-1 (HSV-1) or Acanthamoeba and stored at -70 °C, -20 °C, +4 °C or +35 °C. PCR was performed on days 0, 1, 2, 3, 7 and months 1, 3 and 10 post-inoculation. We found no reduction in the DNA recovery of any of the studied microorganisms for the first 3 days of storage up to +35 °C. For HSV-1 and P. aeruginosa, storage for 3 months at +35 °C was associated with a significant reduction in DNA recovery (P<0.001), but not at +4 °C, -20 °C or -70 °C for 1 month for P. aeruginosa and for 10 months for HSV-1. Acanthamoeba DNA recovery was not affected by any storage parameters (P=0.203). These results will inform the investigation of microbial keratitis where access to microbiological testing is not readily available.
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Affiliation(s)
- Tobi F Somerville
- 1St Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, UK.,2Department of Eye and Vision Sciences, University of Liverpool, Liverpool, UK
| | - Caroline E Corless
- 3Department of Infection and Immunity, Liverpool Clinical Laboratories, Royal Liverpool University Hospital, Liverpool, UK
| | - Timothy Neal
- 3Department of Infection and Immunity, Liverpool Clinical Laboratories, Royal Liverpool University Hospital, Liverpool, UK
| | - Stephen B Kaye
- 1St Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, UK.,2Department of Eye and Vision Sciences, University of Liverpool, Liverpool, UK
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Srinivas SP, Goyal A, Talele DP, Mahadik S, Sudhir RR, Murthy PP, Ranganath S, Kompella UB, Padmanabhan P. Corneal epithelial permeability to fluorescein in humans by a multi-drop method. PLoS One 2018; 13:e0198831. [PMID: 29920519 PMCID: PMC6007839 DOI: 10.1371/journal.pone.0198831] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 05/26/2018] [Indexed: 01/21/2023] Open
Abstract
Purpose The permeability of the corneal epithelium to fluorescein Pdc is an indicator of the health of the ocular surface. It can be measured in a clinical setting by determining the accumulation of fluorescein in the stroma following administration of the dye on the ocular surface. Here we demonstrate a new multi-drop method for the measurement of Pdc by a spot fluorometer. Methods Twenty-nine healthy participants were recruited for this study. First, a probe-drop of fluorescein (0.35%, 2 μL) was instilled on the conjunctiva. The clearance of the dye from the tears was immediately measured using the fluorometer. Following this, two loading drops (2%; 6 μL each) were administered 10 min apart. Fifteen minutes later, the ocular surface was washed and fluorescence from the stroma Fs was measured. Permeability was calculated using Pdc = (Q x Fs)/ (2 x AUC), where Q is the stromal thickness and AUC is the area under the fluorescence vs. time curve for the loading drops. Results After the probe drop, the tear fluorescence followed an exponential decay (elimination rate constant; kd = 0.41 ± 0.28 per min; 49 eyes of 29 subjects), but the increase in Fs was negligible. However, after the loading drops, the measured Fs was ~ 20-fold higher than the autofluorescence and could be recorded at a high signal to noise ratio (SNR > 40). The intra-subject variability of kd was insignificant. Since fluorescein undergoes concentration quenching at > 0.5%, the value of AUC for the loading drops was estimated by scaling the AUC of the probe drop. The calculated Pdc was 0.54 ± 0.54 nm/sec (n = 49). A Monte Carlo simulation of the model for the multi-drop protocol confirmed the robustness of the estimated Pdc. Conclusions The new multi-drop method can be used in place of the single-drop approach. It can overcome a lack of sensitivity in fluorometers of high axial resolution. The Pdc estimated by the multi-drop method is ~ 11-fold higher than previously reported but closer to the value reported for other drugs with equivalent octanol/water partition coefficient.
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Affiliation(s)
- Sangly P. Srinivas
- School of Optometry, Indiana University, Bloomington, Indiana, United States of America
- * E-mail:
| | - Arushi Goyal
- Department of Cornea and Refractive Surgery, Sankara Nethralaya, Chennai, India
| | - Deepti P. Talele
- Department of Cornea and Refractive Surgery, Sankara Nethralaya, Chennai, India
| | - Sanjay Mahadik
- Department of Cornea and Refractive Surgery, Sankara Nethralaya, Chennai, India
| | | | - P. Pavani Murthy
- Department of Cornea and Refractive Surgery, Sankara Nethralaya, Chennai, India
| | - Sudhir Ranganath
- Department of Chemical Engineering, Siddaganga Institute of Technology, Tumkur, India
| | - Uday B. Kompella
- Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Prema Padmanabhan
- Department of Cornea and Refractive Surgery, Sankara Nethralaya, Chennai, India
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Cellular fluorescein hyperfluorescence is dynamin-dependent and increased by Tetronic 1107 treatment. Int J Biochem Cell Biol 2018; 101:54-63. [PMID: 29800726 DOI: 10.1016/j.biocel.2018.05.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 05/04/2018] [Accepted: 05/21/2018] [Indexed: 11/22/2022]
Abstract
Sodium fluorescein ('fluorescein') staining of the ocular surface is frequently an indicator of compromised ocular health, and increases in the presence of certain contact lens multi-purpose solutions (MPS), a phenomenon known as solution induced corneal staining (SICS). The mechanism(s) underpinning fluorescein hyperfluorescence are uncertain, though may reflect increased cellular uptake of fluorescein by corneal epithelial cells. We have developed an in vitro model to study fluorescein uptake in both 'generic' mammalian cells (murine fibroblasts) and human corneal cells. Fluorescein hyperfluorescence increased after treatment with two MPS associated with clinical corneal fluorescein staining, yet there was no cellular hyperfluorescence for two MPS that do not cause this staining. Increased fluorescein uptake did not correlate with presence of a necrotic or an apoptotic marker (propidium iodide and caspase-3 respectively). Incubation of MPS-treated cells with dynasore (an inhibitor of dynamin, implicated in endocytic pathways) reduced fluorescein uptake irrespective of MPS treatment. The non-ionic surfactant Tetronic 1107 (present in both MPS associated with corneal fluorescein staining) increased uptake of fluorescein for both cell types, whereas an unrelated surfactant (Triton X-100) did not. We conclude that the clinical hyperfluorescence profile observed after exposure to four MPS can be reproduced using a simple model of cellular fluorescein uptake, suggesting this is the biological basis for SICS. Fluorescein entry does not correlate with necrosis or apoptosis, but instead involves a dynamin-dependent active process. Moreover the surfactant Tetronic 1107 appears to be a key MPS constituent triggering increased fluorescein entry, and may be the major factor responsible for SICS.
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Bron AJ, de Paiva CS, Chauhan SK, Bonini S, Gabison EE, Jain S, Knop E, Markoulli M, Ogawa Y, Perez V, Uchino Y, Yokoi N, Zoukhri D, Sullivan DA. TFOS DEWS II pathophysiology report. Ocul Surf 2017; 15:438-510. [PMID: 28736340 DOI: 10.1016/j.jtos.2017.05.011] [Citation(s) in RCA: 925] [Impact Index Per Article: 132.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 05/26/2017] [Indexed: 12/18/2022]
Abstract
The TFOS DEWS II Pathophysiology Subcommittee reviewed the mechanisms involved in the initiation and perpetuation of dry eye disease. Its central mechanism is evaporative water loss leading to hyperosmolar tissue damage. Research in human disease and in animal models has shown that this, either directly or by inducing inflammation, causes a loss of both epithelial and goblet cells. The consequent decrease in surface wettability leads to early tear film breakup and amplifies hyperosmolarity via a Vicious Circle. Pain in dry eye is caused by tear hyperosmolarity, loss of lubrication, inflammatory mediators and neurosensory factors, while visual symptoms arise from tear and ocular surface irregularity. Increased friction targets damage to the lids and ocular surface, resulting in characteristic punctate epithelial keratitis, superior limbic keratoconjunctivitis, filamentary keratitis, lid parallel conjunctival folds, and lid wiper epitheliopathy. Hybrid dry eye disease, with features of both aqueous deficiency and increased evaporation, is common and efforts should be made to determine the relative contribution of each form to the total picture. To this end, practical methods are needed to measure tear evaporation in the clinic, and similarly, methods are needed to measure osmolarity at the tissue level across the ocular surface, to better determine the severity of dry eye. Areas for future research include the role of genetic mechanisms in non-Sjögren syndrome dry eye, the targeting of the terminal duct in meibomian gland disease and the influence of gaze dynamics and the closed eye state on tear stability and ocular surface inflammation.
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Affiliation(s)
- Anthony J Bron
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; Vision and Eye Research Unit, Anglia Ruskin University, Cambridge, UK.
| | - Cintia S de Paiva
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, USA
| | - Sunil K Chauhan
- Schepens Eye Research Institute & Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Stefano Bonini
- Department of Ophthalmology, University Campus Biomedico, Rome, Italy
| | - Eric E Gabison
- Department of Ophthalmology, Fondation Ophtalmologique Rothschild & Hôpital Bichat Claude Bernard, Paris, France
| | - Sandeep Jain
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Erich Knop
- Departments of Cell and Neurobiology and Ocular Surface Center Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Maria Markoulli
- School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
| | - Yoko Ogawa
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Victor Perez
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami, Miami, FL, USA
| | - Yuichi Uchino
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Norihiko Yokoi
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Driss Zoukhri
- Tufts University School of Dental Medicine, Boston, MA, USA
| | - David A Sullivan
- Schepens Eye Research Institute & Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
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Squamous epitheliotropism of Enterovirus A71 in human epidermis and oral mucosa. Sci Rep 2017; 7:45069. [PMID: 28322333 PMCID: PMC5359612 DOI: 10.1038/srep45069] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 02/16/2017] [Indexed: 12/31/2022] Open
Abstract
Hand-foot-and-mouth disease is a self-limiting paediatric infectious disease commonly caused by Enterovirus A71 (Genus: Enterovirus, Family: Picornaviridae). Typical lesions in and around the hands, feet, oral cavity and other places may rarely be complicated by acute flaccid paralysis and acute encephalomyelitis. Although virus is readily cultured from skin vesicles and oral secretions, the cellular target/s of Enterovirus A71 in human skin and oral mucosa are unknown. In Enterovirus A71-infected human skin and oral mucosa organotypic cultures derived from the prepuce and lip biopsies, focal viral antigens and viral RNA were localized to cytoplasm of epidermal and mucosal squamous cells as early as 2 days post-infection. Viral antigens/RNA were associated with cytoplasmic vacuolation and cellular necrosis. Infected primary prepuce epidermal keratinocyte cultures showed cytopathic effects with concomitant detection of viral antigens from 2 days post-infection. Supernatant and/or tissue homogenates from prepuce skin organotypic cultures and primary prepuce keratinocyte cultures showed viral titres consistent with active viral replication. Our data strongly support Enterovirus A71 squamous epitheliotropism in the human epidermis and oral mucosa, and suggest that these organs are important primary and/or secondary viral replication sites that contribute significantly to oral and cutaneous viral shedding resulting in person-to-person transmission, and viraemia, which could lead to neuroinvasion.
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Pilot Study to Determine the Effect of Lens and Eye Rinsing on Solution-Induced Corneal Staining (SICS). Optom Vis Sci 2016; 93:1218-27. [PMID: 27441740 DOI: 10.1097/opx.0000000000000933] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE The main purpose of this study was to determine whether two interventions (rinsing the lens before lens insertion and rinsing the ocular surface post-lens removal) had any impact on solution-induced corneal staining (SICS). In addition, the presence of hyper-reflective epithelial cells in the presence of SICS was investigated. METHODS Twenty subjects wore new balafilcon A lenses, which had been soaked overnight in a multipurpose care product containing polyhexamethylene biguanide for 2 hours. The study was conducted across three phases. In phase 1 (investigator and subject masked, randomized eye), one lens was rinsed with nonpreserved saline before lens insertion. In phase 2 (investigator masked, randomized eye), one eye was rinsed with nonpreserved saline after lens removal, before staining assessment. Corneal staining was recorded as the percentage area of the cornea exhibiting superficial punctate staining. In both phases, ocular comfort and presence of specific symptoms were captured. In phase 3, there was no randomized treatment; confocal images of the epithelium were obtained after 2 hours of wear. RESULTS In phase 1 (lens-rinse), there was no significant difference in staining between the treated and untreated eyes (84 vs. 92%, respectively; p = 0.06). In phase 2 (eye-rinse), there was also no significant difference between the treated and untreated eye (86 vs. 86%, p = 0.92). Most subjects were asymptomatic. In phase 3, images of hyper-reflective cells were captured in 97% of the eyes imaged. CONCLUSIONS The two rinsing procedures did not affect the level of the SICS response. Hyper-reflective epithelial cells were found to be present in a significant number of eyes exhibiting SICS, and their presence warrants further investigation.
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Fini ME, Bauskar A, Jeong S, Wilson MR. Clusterin in the eye: An old dog with new tricks at the ocular surface. Exp Eye Res 2016; 147:57-71. [PMID: 27131907 DOI: 10.1016/j.exer.2016.04.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 04/22/2016] [Accepted: 04/23/2016] [Indexed: 12/30/2022]
Abstract
The multifunctional protein clusterin (CLU) was first described in 1983 as a secreted glycoprotein present in ram rete testis fluid that enhanced aggregation ('clustering') of a variety of cells in vitro. It was also independently discovered in a number of other systems. By the early 1990s, CLU was known under many names and its expression had been demonstrated throughout the body, including in the eye. Its homeostatic activities in proteostasis, cytoprotection, and anti-inflammation have been well documented, however its roles in health and disease are still not well understood. CLU is prominent at fluid-tissue interfaces, and in 1996 it was demonstrated to be the most highly expressed transcript in the human cornea, the protein product being localized to the apical layers of the mucosal epithelia of the cornea and conjunctiva. CLU protein is also present in human tears. Using a preclinical mouse model for desiccating stress that mimics human dry eye disease, the authors recently demonstrated that CLU prevents and ameliorates ocular surface barrier disruption by a remarkable sealing mechanism dependent on attainment of a critical all-or-none concentration in the tears. When the CLU level drops below the critical all-or-none threshold, the barrier becomes vulnerable to desiccating stress. CLU binds selectively to the ocular surface subjected to desiccating stress in vivo, and in vitro to LGALS3 (galectin-3), a key barrier component. Positioned in this way, CLU not only physically seals the ocular surface barrier, but it also protects the barrier cells and prevents further damage to barrier structure. CLU depletion from the ocular surface epithelia is seen in a variety of inflammatory conditions in humans and mice that lead to squamous metaplasia and a keratinized epithelium. This suggests that CLU might have a specific role in maintaining mucosal epithelial differentiation, an idea that can now be tested using the mouse model for desiccating stress. Most excitingly, the new findings suggest that CLU could serve as a novel biotherapeutic for dry eye disease.
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Affiliation(s)
- M Elizabeth Fini
- USC Institute for Genetic Medicine and Departments of Cell & Neurobiology and Ophthalmology, Keck School of Medicine of USC, University of Southern California, 2250 Alcatraz St., Suite 240, Los Angeles, CA 90089-9037, USA.
| | - Aditi Bauskar
- USC Institute for Genetic Medicine and Graduate Program in Medical Biology, Keck School of Medicine of USC, University of Southern California, 2250 Alcatraz St., Suite 240, Los Angeles, CA 90089-9037, USA.
| | - Shinwu Jeong
- USC Institute for Genetic Medicine and Department of Ophthalmology, Keck School of Medicine of USC, University of Southern California, 2250 Alcatraz St., Suite 240, Los Angeles, CA 90089-9037, USA.
| | - Mark R Wilson
- Illawarra Health and Medical Research Institute, School of Biological Sciences, University of Wollongong, Northfields Avenue, Wollongong, New South Wales, 2522 Australia.
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Fluorescence lifetime imaging microscopy reveals quenching of fluorescein within corneal epithelium. Exp Eye Res 2016; 147:12-19. [PMID: 27106141 DOI: 10.1016/j.exer.2016.04.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/08/2016] [Accepted: 04/14/2016] [Indexed: 11/22/2022]
Abstract
Topical application of fluorescein results in background fluorescence of normal corneal epithelial cells. The fluorescence appears relatively weak and is often ignored clinically. The concentrations of fluorescein applied clinically exceed the threshold for self quenching. The possibility that exuberant topical concentrations of fluorescein result in quenching of fluorescence in tears and normal corneal epithelium is explored. Fluorescence lifetime measurements are sensitive to quenching and are less vulnerable to inner filter effect than steady state measurements. The types of fluorescence lifetime quenching often report informative molecular interactions. Therefore, fluorescence lifetime confocal imaging was performed in solutions, tears and corneal epithelium removed by membrane cytology following applied fluorescein. Amplitude averaged fluorescence lifetimes (τamp) were measured with time resolved single photon counting using a pulsed diode laser for excitation of fluorescein. Lifetime decays were fit to multi-exponential models with least squares analysis. Stern-Volmer plots for both intensity (I) and (τamp) were determined. Stern-Volmer plots demonstrated both dynamic and static quenching components (R(2) = 0.98 exponential fit, I0/I). Plots of τamp versus concentration of fluorescein revealed a linear relationship. Immediately after fluorescein application, quenching was evident in tears (τamp < 1 ns) versus tears sampled after 5 min (τamp = 3.7 ns). Corneal epithelium showed quenching (τamp ≤ 2 ns) from 1 to 16 min post fluorescein instillation. Clinical concentrations of fluorescein show self-quenching but rapidly dilute as tears turnover. Intracellular quenching occurs in normal corneal epithelium. Lifetime decay curves suggest complex mechanisms are involved. Quenching is a plausible explanation for the low fluorescence background observed clinically.
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Efron N, Brennan NA, Morgan PB, Wilson T. Lid wiper epitheliopathy. Prog Retin Eye Res 2016; 53:140-174. [PMID: 27094372 DOI: 10.1016/j.preteyeres.2016.04.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/05/2016] [Accepted: 04/12/2016] [Indexed: 01/12/2023]
Abstract
Some recent research has resulted in a hypothesis that there is a common 'lid wiper' region that is apposite to the ocular surface or anterior lens surface (where contact lenses are worn), responsible for spreading tears during blinking. In the upper eyelid, it extends about 0.6 mm from the crest of the sharp posterior (inner) lid border (i.e. the mucocutaneous junction, or line of Marx) to the subtarsal fold superiorly and from the medial upper punctum to the lateral canthus horizontally. Histologically, it is seen as an epithelial elevation comprising of stratified epithelium with a transitional conjunctival structure of (moving posteriorly) squamous cells then cuboidal cells, with some parakeratinised cells and goblet cells. Lid wiper epitheliopathy (LWE) denotes staining of the lid wiper observed after instillation of dyes such as fluorescein, rose bengal or lissamine green. There have been some reports of higher rates of LWE in dry eye patients and contact lens wearers, but others have failed to find such associations. The primary cause of LWE is thought to be increased friction between the lid wiper and ocular or anterior contact lens surface due to inadequate lubrication, which could be caused by dry eye and may be exacerbated by factors such as abnormal blinking patterns, poor contact lens surface lubricity and adverse environmental influences. Recent evidence suggests that LWE is associated with sub-clinical inflammation. LWE has the potential to provide the missing mechanistic link between clinical observation and symptoms associated with dry eye and contact lens wear. Clinical and fundamental research into LWE is still in its infancy and in many instances equivocal; however, it is an idea that provides a potentially important new avenue for further investigation of anterior eye discomfort associated with ocular dryness and contact lens wear.
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Affiliation(s)
- Nathan Efron
- Institute of Health and Biomedical Innovation, School of Optometry and Vision Science, Queensland University of Technology, 60 Musk Avenue, Kelvin Grove, Queensland 4059, Australia.
| | - Noel A Brennan
- Johnson & Johnson Vision Care, Inc., 7500 Centurion Parkway, Jacksonville, FL 32256, USA
| | - Philip B Morgan
- Eurolens Research, The University of Manchester, Dover Street, Manchester, M13 9PL, UK
| | - Tawnya Wilson
- Johnson & Johnson Vision Care, Inc., 7500 Centurion Parkway, Jacksonville, FL 32256, USA
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Bauskar A, Mack WJ, Mauris J, Argüeso P, Heur M, Nagel BA, Kolar GR, Gleave ME, Nakamura T, Kinoshita S, Moradian-Oldak J, Panjwani N, Pflugfelder SC, Wilson MR, Fini ME, Jeong S. Clusterin Seals the Ocular Surface Barrier in Mouse Dry Eye. PLoS One 2015; 10:e0138958. [PMID: 26402857 PMCID: PMC4581869 DOI: 10.1371/journal.pone.0138958] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 09/04/2015] [Indexed: 12/02/2022] Open
Abstract
Dry eye is a common disorder caused by inadequate hydration of the ocular surface that results in disruption of barrier function. The homeostatic protein clusterin (CLU) is prominent at fluid-tissue interfaces throughout the body. CLU levels are reduced at the ocular surface in human inflammatory disorders that manifest as severe dry eye, as well as in a preclinical mouse model for desiccating stress that mimics dry eye. Using this mouse model, we show here that CLU prevents and ameliorates ocular surface barrier disruption by a remarkable sealing mechanism dependent on attainment of a critical all-or-none concentration. When the CLU level drops below the critical all-or-none threshold, the barrier becomes vulnerable to desiccating stress. CLU binds selectively to the ocular surface subjected to desiccating stress in vivo, and in vitro to the galectin LGALS3, a key barrier component. Positioned in this way, CLU not only physically seals the ocular surface barrier, but it also protects the barrier cells and prevents further damage to barrier structure. These findings define a fundamentally new mechanism for ocular surface protection and suggest CLU as a biotherapeutic for dry eye.
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Affiliation(s)
- Aditi Bauskar
- USC Institute for Genetic Medicine and Graduate Program in Medical Biology, Keck School of Medicine of USC, University of Southern California, Los Angeles, California, United States of America
| | - Wendy J. Mack
- Southern California Clinical & Translational Science Institute and Department of Preventive Medicine, Keck School of Medicine of USC, University of Southern California, Los Angeles, California, United States of America
| | - Jerome Mauris
- The Schepens Eye Research Institute, Massachusetts Eye & Ear and Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Pablo Argüeso
- The Schepens Eye Research Institute, Massachusetts Eye & Ear and Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Martin Heur
- USC Eye Institute, Keck School of Medicine of USC, University of Southern California, Los Angeles, California, United States of America
| | - Barbara A. Nagel
- Research Microscopy and Histology Core, Department of Pathology, Saint Louis University School of Medicine, St Louis, Missouri, United States of America
| | - Grant R. Kolar
- Department of Pathology and Department of Ophthalmology, Saint Louis University School of Medicine, St. Louis, Missouri, United States of America
| | - Martin E. Gleave
- The Vancouver Prostate Centre and Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Takahiro Nakamura
- Department of Frontier Medical Science and Technology for Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Shigeru Kinoshita
- Department of Frontier Medical Science and Technology for Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology, Division of Biomedical Sciences, University of Southern California, Herman Ostrow School of Dentistry of USC, Los Angeles, California, United States of America
| | - Noorjahan Panjwani
- New England Eye Center/Department of Ophthalmology and Department of Developmental, Molecular & Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Stephen C. Pflugfelder
- Ocular Surface Center, Department of Ophthalmology, Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, United States of America
| | - Mark R. Wilson
- Illawarra Health and Medical Research Institute, School of Biological Sciences, University of Wollongong, Wollongong, New South Wales, Australia
| | - M. Elizabeth Fini
- USC Institute for Genetic Medicine and Departments of Cell & Neurobiology and Ophthalmology, Keck School of Medicine of USC, University of Southern California, Los Angeles, California, United States of America
| | - Shinwu Jeong
- USC Institute for Genetic Medicine and Department of Ophthalmology, Keck School of Medicine of USC, University of Southern California, Los Angeles, California, United States of America
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Bayesian-based deconvolution fluorescence microscopy using dynamically updated nonstationary expectation estimates. Sci Rep 2015; 5:10849. [PMID: 26054051 PMCID: PMC4459105 DOI: 10.1038/srep10849] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 04/30/2015] [Indexed: 11/23/2022] Open
Abstract
Fluorescence microscopy is widely used for the study of biological specimens. Deconvolution can significantly improve the resolution and contrast of images produced using fluorescence microscopy; in particular, Bayesian-based methods have become very popular in deconvolution fluorescence microscopy. An ongoing challenge with Bayesian-based methods is in dealing with the presence of noise in low SNR imaging conditions. In this study, we present a Bayesian-based method for performing deconvolution using dynamically updated nonstationary expectation estimates that can improve the fluorescence microscopy image quality in the presence of noise, without explicit use of spatial regularization.
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Nishida T, Inui M, Nomizu M. Peptide therapies for ocular surface disturbances based on fibronectin-integrin interactions. Prog Retin Eye Res 2015; 47:38-63. [PMID: 25645519 DOI: 10.1016/j.preteyeres.2015.01.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Revised: 01/18/2015] [Accepted: 01/21/2015] [Indexed: 11/24/2022]
Abstract
The condition of the corneal epithelium is a critical determinant of corneal transparency and clear vision. The corneal epithelium serves as a barrier to protect the eye from external insults, with its smooth surface being essential for its optical properties. Disorders of the corneal epithelium include superficial punctate keratopathy, corneal erosion, and persistent epithelial defects (PEDs). The prompt resolution of these disorders is important for minimization of further damage to the cornea. Currently available treatment modalities for corneal epithelial disorders are based on protection of the ocular surface in order to allow natural healing to proceed. PEDs remain among the most difficult corneal conditions to treat, however. On the basis of characterization of the pathobiology of PEDs at the cell and molecular biological levels, we have strived to develop new modes of treatment for these defects. These treatments rely on two key concepts: provision of a substrate, such as the adhesive glycoprotein fibronectin, for the attachment and migration of corneal epithelial cells, and activation of these cells by biological agents such as the combination of substance P and insulin-like growth factor-1 (IGF-1). Central to both approaches is the role of the fibronectin-integrin system in corneal epithelial wound healing. Determination of the minimum amino acid sequences required for the promotion of corneal epithelial wound closure by fibronectin (PHSRN) and by substance P (FGLM-amide) plus IGF-1 (SSSR) has led to the development of peptide eyedrops for the treatment of PEDs that are free of adverse effects of the parent molecules.
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Affiliation(s)
- Teruo Nishida
- Ohshima Hospital of Ophthalmology, 11-8 Kamigofuku, Hakata-ku, Fukuoka 812-0036, Japan; Yamaguchi University, 1-1-1 Minami-kogushi, Ube City, Yamaguchi 755-8505, Japan.
| | - Makoto Inui
- Department of Pharmacology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-kogushi, Ube City, Yamaguchi 755-8505, Japan
| | - Motoyoshi Nomizu
- Laboratory of Clinical Biochemistry, School of Pharmacy, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
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Bron A, Argüeso P, Irkec M, Bright F. Clinical staining of the ocular surface: Mechanisms and interpretations. Prog Retin Eye Res 2015; 44:36-61. [DOI: 10.1016/j.preteyeres.2014.10.001] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 10/08/2014] [Accepted: 10/08/2014] [Indexed: 10/24/2022]
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Fluorescein staining and physiological state of corneal epithelial cells. Cont Lens Anterior Eye 2014; 37:213-23. [DOI: 10.1016/j.clae.2013.11.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Revised: 09/01/2013] [Accepted: 11/20/2013] [Indexed: 11/17/2022]
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Novakofski KD, Williams RM, Fortier LA, Mohammed HO, Zipfel WR, Bonassar LJ. Identification of cartilage injury using quantitative multiphoton microscopy. Osteoarthritis Cartilage 2014; 22:355-62. [PMID: 24185113 PMCID: PMC4117377 DOI: 10.1016/j.joca.2013.10.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 08/27/2013] [Accepted: 10/23/2013] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Cartilage injury can lead to post-traumatic osteoarthritis (PTOA). Immediate post-trauma cellular and structural changes are not widely understood. Furthermore, current cellular-resolution cartilage imaging techniques require sectioning of cartilage and/or use of dyes not suitable for patient imaging. In this study, we used multiphoton microscopy (MPM) data with FDA-approved sodium fluorescein to identify and evaluate the pattern of chondrocyte death after traumatic injury. METHOD Mature equine distal metacarpal or metatarsal osteochondral blocks (OCBs) were injured by 30 MPa compressive loading delivered over 1 s. Injured and control sites were imaged unfixed and in situ 1 h post-injury with sodium fluorescein using rasterized z-scanning. MPM data was quantified in MATLAB, reconstructed in 3-D, and projected in 2-D to determine the damage pattern. RESULTS MPM images (600 per sample) were reconstructed and analyzed for cell death. The overall distribution of cell death appeared to cluster into circular (n = 7) or elliptical (n = 4) patterns (p = 0.006). Dead cells were prevalent near cracks in the matrix, with only 26.3% (SE = 5.0%, p < 0.0001) of chondrocytes near cracks being viable. CONCLUSION This study demonstrates the first application of MPM for evaluating cellular-scale cartilage injury in situ in live tissue, with clinical potential for detecting early cartilage damage. With this technique, we were able to uniquely observe two death patterns resulting from the same compressive loading, which may be related to local variability in matrix structure. These results also demonstrate proof-of-concept MPM diagnostic use in detecting subtle and early cartilage damage not detectable in any other way.
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Affiliation(s)
| | - Rebecca M. Williams
- Department of Biomedical Engineering, Cornell University, Ithaca, New York 14853
| | - Lisa A. Fortier
- Department of Clinical Sciences, Cornell University, Ithaca, New York
| | - Hussni O. Mohammed
- Population Medicine and Diagnostic Sciences, Cornell University, Ithaca, New York 14853, Cornell University, Ithaca, New York 14853
| | - Warren R. Zipfel
- Department of Biomedical Engineering, Cornell University, Ithaca, New York 14853
| | - Lawrence J. Bonassar
- Department of Biomedical Engineering, Cornell University, Ithaca, New York 14853
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Bakkar MM, Hardaker L, March P, Morgan PB, Maldonado-Codina C, Dobson CB. The cellular basis for biocide-induced fluorescein hyperfluorescence in mammalian cell culture. PLoS One 2014; 9:e84427. [PMID: 24489650 PMCID: PMC3904830 DOI: 10.1371/journal.pone.0084427] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 11/14/2013] [Indexed: 11/18/2022] Open
Abstract
Clinical examination of the ocular surface is commonly carried out after application of sodium fluorescein in both veterinary and medical practice by assessing the resulting 'staining'. Although localized intensely stained regions of the cornea frequently occur after exposure to 'adverse' clinical stimuli, the cell biology underlying this staining is unknown, including whether intense fluorescein staining indicates the presence of damaged cells. Ocular exposure to certain contact lens multipurpose solutions (MPS) gives rise to intense fluorescein staining referred to as solution induced corneal staining (SICS), and we have made use of this phenomenon with Vero and L929 cell culture models to investigate the fundamental biology of fluorescein interactions with cells. We found that all cells take up fluorescein, however a sub-population internalize much higher levels, giving rise to brightly staining 'hyperfluorescent' cells within the treated cultures, which contain fluorescein throughout the cell cytoplasm and nucleus. The numbers of these hyperfluorescent cells are significantly increased after exposure to MPS associated with SICS. Surprisingly, hyperfluorescent cells did not show higher levels of staining with propidium iodide, a marker of lysed cells. Consistently, treatment with the cytolytic toxin benzalkonium chloride resulted in almost all cells staining with propidium iodide, and the complete abolition of fluorescein hyperfluorescence. Finally we found that internalization of fluorescein and its loss from treated cells both require cellular activity, as both processes were halted after incubation at 4 °C. We conclude that fluorescein hyperfluorescence can be replicated in three diverse cell cultures, and is increased by MPS-treatment, as occurs clinically. The process involves the concentration of fluorescein by a sub-population of cells that are active, and does not occur in lysed cells. Our data suggest that corneal staining in the clinic reflects active living cells, and is not directly caused by dead cells being produced in response to adverse clinical stimuli.
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Affiliation(s)
- May M. Bakkar
- Eurolens Research, Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
- Medical Device Biology Group, Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
| | - Luke Hardaker
- Medical Device Biology Group, Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
| | - Peter March
- Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
| | - Philip B. Morgan
- Eurolens Research, Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
- Medical Device Biology Group, Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
| | - Carole Maldonado-Codina
- Eurolens Research, Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
- Medical Device Biology Group, Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
| | - Curtis B. Dobson
- Medical Device Biology Group, Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
- * E-mail:
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Chronic dry eye disease is principally mediated by effector memory Th17 cells. Mucosal Immunol 2014; 7:38-45. [PMID: 23571503 PMCID: PMC3732510 DOI: 10.1038/mi.2013.20] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 03/07/2013] [Indexed: 02/08/2023]
Abstract
Recent experimental and clinical data suggest that there is a link between dry eye disease (DED) and T-cell-mediated immunity. However, whether these immune responses are a consequence or cause of ocular surface inflammation remains to be determined. Thus far, only models of acute DED have been used to derive experimental data. This is in contrast to clinical DED which usually presents as a chronic disease. In the present study, using a murine model of chronic DED, it was established that the chronic phase of the disease is accompanied by T helper type 17 (Th17) responses at the ocular surface and that a significant memory T-cell population can be recovered from chronic DED. This memory response is predominantly mediated by Th17 cells. Moreover, adoptive transfer of this memory T-cell population was shown to induce more severe and rapidly progressing DED than did the adoptive transfer of its effector or naive counterparts. Not only do these results clearly demonstrate that effector memory Th17 cells are primarily responsible for maintaining the chronic and relapsing course of DED, but they also highlight a potentially novel therapeutic strategy for targeting memory immune responses in patients with DED.
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Gorbet M, Peterson R, McCanna D, Woods C, Jones L, Fonn D. Human Corneal Epithelial Cell Shedding and Fluorescein Staining in Response to Silicone Hydrogel Lenses and Contact Lens Disinfecting Solutions. Curr Eye Res 2013; 39:245-56. [DOI: 10.3109/02713683.2013.841255] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Efron N, Brennan NA, Bright FV, Glasgow BJ, Jones LW, Sullivan DA, Tomlinson A, Zhang J. 2. Contact lens care and ocular surface homeostasis. Cont Lens Anterior Eye 2013; 36 Suppl 1:S9-13. [PMID: 23347575 DOI: 10.1016/s1367-0484(13)60004-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The early focus of contact lens wear and ocular health was on oxygen delivery. However, as we learn more about how the eye works, and investigate how the contact lens interacts with the cornea, the role of the tear film has risen in prominence. A healthy tear film is critical for normal ocular homeostasis, and abnormalities of the tear film are the primary cause of dry eye. In order to improve patient eye health and comfort during lens wear, we need to further elucidate the relationship among contact lenses, contact lens solutions, the tear film, and the corneal epithelium, and find ways to maintain homeostasis of the ocular surface. In this section, we review the latest data and opinions on this complex relationship between contact lenses and lens care solutions.
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Affiliation(s)
- Nathan Efron
- Queensland University of Technology, Institute of Health and Biomedical Innovation, Kelvin Grove, Queensland, Australia
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Yeh PT, Casey R, Glasgow BJ. A novel fluorescent lipid probe for dry eye: retrieval by tear lipocalin in humans. Invest Ophthalmol Vis Sci 2013; 54:1398-410. [PMID: 23361507 DOI: 10.1167/iovs.12-10817] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE A fluorescent probe was used to identify mucin-depleted areas on the ocular surface and to test the hypothesis that tear lipocalin retrieves lipids from the eyes of normal and dry eye subjects. METHODS Fluorescein-labeled octadecyl ester, FODE, was characterized by mass spectrometry and absorbance spectrophotometry. The use of FODE to define mucin defects was studied with impression membranes under conditions that selectively deplete mucin. The kinetics of FODE removal from the ocular surface were analyzed by sampling tears from control and dry eye patients at various times. The tear protein-FODE complexes were isolated by gel filtration and ion exchange chromatographies, monitored with absorption and fluorescent spectroscopies, and analyzed by gel electrophoresis. Immunoprecipitation verified FODE complexed to tear lipocalin in tears. RESULTS FODE exhibits an isosbestic point at 473 nm, pKa of 7.5, and red shift relative to fluorescein. The low solubility of FODE in buffer is enhanced with 1% Tween 80 and ethanol. FODE adheres to the ocular surface of dry eye patients. FODE produces visible staining at the contact sites of membranes, which correlates with removal of mucin. Despite the fact that tear lipocalin is reduced in dry eye patients, FODE removal follows similar rapid exponential decay functions for all subjects. FODE is bound to tear lipocalin in tears. CONCLUSIONS Tear lipocalin retrieves lipid rapidly from the human ocular surface in mild to moderate dry eye disease and controls. With improvements in solubility, FODE may have potential as a fluorescent probe to identify mucin-depleted areas.
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Affiliation(s)
- Po-Ting Yeh
- Departments of Ophthalmology and Pathology and Laboratory Medicine, David Geffen School of Medicine at University of California-Los Angeles, Jules Stein Eye Institute, Los Angeles, California 90095, USA
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Narayanan S, Redfern RL, Miller WL, Nichols KK, McDermott AM. Dry eye disease and microbial keratitis: is there a connection? Ocul Surf 2013; 11:75-92. [PMID: 23583043 DOI: 10.1016/j.jtos.2012.12.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 12/14/2012] [Accepted: 12/16/2012] [Indexed: 02/07/2023]
Abstract
Dry eye is a common ocular surface disease of multifactorial etiology characterized by elevated tear osmolality and inflammation leading to a disrupted ocular surface. The latter is a risk factor for ocular surface infection, yet overt infection is not commonly seen clinically in the typical dry eye patient. This suggests that important innate mechanisms operate to protect the dry eye from invading pathogens. This article reviews the current literature on epidemiology of ocular surface infection in dry eye patients and laboratory-based studies on innate immune mechanisms operating at the ocular surface and their alterations in human dry eye and animal models. The review highlights current understanding of innate immunity in dry eye and identifies gaps in our knowledge to help direct future studies to further unravel the complexities of dry eye disease and its sequelae.
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Affiliation(s)
- Srihari Narayanan
- University of the Incarnate Word, Rosenberg School of Optometry, San Antonio, TX, USA
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A Preservative-and-Fluorescein Interaction Model for Benign Multipurpose Solution–Associated Transient Corneal Hyperfluorescence. Cornea 2012; 31:1480-8. [DOI: 10.1097/ico.0b013e31824a2083] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Nichols JJ, King-Smith PE, Hinel EA, Thangavelu M, Nichols KK. The use of fluorescent quenching in studying the contribution of evaporation to tear thinning. Invest Ophthalmol Vis Sci 2012; 53:5426-32. [PMID: 22789918 DOI: 10.1167/iovs.12-10033] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The purpose of our study was to test the prediction that if the tear film thins due to evaporation, rather than tangential flow, a high concentration of fluorescein in the tear film would show a greater reduction in fluorescent intensity compared to a low concentration of fluorescein due to self-quenching at high concentrations. METHODS Tear film thickness, thinning rate, and fluorescent intensity were measured continuously and simultaneously with a modified spectral interferometer in 30 healthy subjects with two different concentrations (2% followed by 10%) of 1 μL of liquid fluorescein on the eye. Measurements of fluorescein self-quenching (fluorescent efficiency as a function of fluorescein concentration) are described in an Appendix and are reported in arbitrary units. RESULTS Under low and high fluorescein concentration conditions, there were no differences in tear film thickness (P = 0.09) or thinning rates (P = 0.76). While the mean initial fluorescent intensity was similar between groups (637.47 ± 381.47 vs. 672.09 ± 649.72, P = 0.55), the mean rate of fluorescent decay was 4-fold faster in the high (16.57 ± 29.34) than in the low (4.11 ± 6.78) concentration group (P < 0.01). CONCLUSIONS The large difference in the rate of fluorescent decay between groups can be explained by the effects of evaporation and self quenching of fluorescein; the latter is expected to be greater for high than for low fluorescein concentration. Fluorescence decay due to tangential flow would be expected to be similar at high and low fluorescein concentrations. This supports previous evidence that evaporation has the primary role in normal tear thinning between blinks.
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Affiliation(s)
- Jason J Nichols
- College of Optometry, University of Houston, Houston, TX 77204, USA.
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Localization and expression of zonula occludins-1 in the rabbit corneal epithelium following exposure to benzalkonium chloride. PLoS One 2012; 7:e40893. [PMID: 22815857 PMCID: PMC3399810 DOI: 10.1371/journal.pone.0040893] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Accepted: 06/18/2012] [Indexed: 02/07/2023] Open
Abstract
Preservatives are a major component of the ophthalmic preparations in multi-dose bottles. The purpose of this study was to investigate the acute effect of benzalkonium chloride (BAC), a common preservative used in ophthalmic preparations, on the localization and expression of zonula occludens (ZO)-1 in the rabbit corneal epithelium in vivo. BAC at 0.005%, 0.01%, or 0.02% was topically applied to one eye each of albino rabbits at 5 min intervals for a total of 3 times. The contralateral untreated eyes served as controls. The following clinical indications were evaluated: Schirmer test, tear break-up time (BUT), fluorescein and rose Bengal staining. The structure of central cornea was examined by in vivo confocal microscopy, and the corneal barrier function was evaluated by measurement of corneal transepithelial electrical resistance and permeability to carboxy fluorescein. Whole mount corneas were analyzed by using fluorescence confocal microscopy for the presence of ZO-1, 2, occludin, claudin-1, Ki67 and cell apoptosis in the epithelium. The expression of ZO-1 in the corneal epithelium was also examined by western blot and reverse transcription-polymerase chain reaction analyses. Exposure to BAC resulted in higher rose Bengal staining scores while no significant changes in BUT, Schirmer and corneal florescein scores. It also induced corneal epithelial cell damage, dispersion of ZO-1 and ZO-2 from their normal locus at the superficial layer and disruption of epithelial barrier function. However, the amounts of ZO-1 mRNA and protein in the corneal epithelium were not affected by BAC treatment. Exposure to BAC can quickly impair the corneal epithelium without tear deficiency. BAC disrupts the tight junctions of corneal epithelium between superficial cells in the rabbit corneal epithelium in vivo.
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Schrage N, Frentz M, Spoeler F. The Ex Vivo Eye Irritation Test (EVEIT) in evaluation of artificial tears: Purite-preserved versus unpreserved eye drops. Graefes Arch Clin Exp Ophthalmol 2012; 250:1333-40. [PMID: 22580989 DOI: 10.1007/s00417-012-1999-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Revised: 03/04/2012] [Accepted: 03/06/2012] [Indexed: 11/28/2022] Open
Abstract
OBJECTIVE Preservatives in artificial tears cause controversy. New developments such as the Purite system have been introduced into the market, with the promise of little damage to the corneal surface. We wanted to give insight into the differences in the effect of preserved and unpreserved artifical tears on rabbit corneas cultured with the Ex Vivo Eye Irritation Test (EVEIT) system. MATERIALS We compared the two artifical tears products Hylo Comod and Optive being dropped for 72 hours each hour one drop onto the corneal surface. METHODS Each cornea was mechanically wounded with four epithelial defects on each cornea with a size of 3 to 4.5 mm(2). With n = 4 corneas in the Hylo-Comod and n = 4 corneas in the Optive group, we exposed the corneal surfaces to repeated doses of these artificial tears for 3 days. We observed healing of corneal erosions and surface epithelial integrity with sodium-fluoresceine staining under cobalt blue light illumination. RESULTS We found nearly complete healing of epithelial defects with both artificial tears. The Hylo-Comod group healed significantly faster. After 72 hours, the vast majority of epithelial defects were closed. All corneas exposed to Purite showed superficial stippling, whereas the HyloComod group did not show any stippling of the cornea; this difference was significant. DISCUSSION Epithelial healing and recovery in the EVEIT system is observed in both groups, confirming the concept of artificial tears as a supporting factor of corneal health and healing. The superficial stippling of the corneal epithelium was observed only in the Optive group. This effect is considered as a marker of dry eye syndrome, and should be prevented by the application of artificial tears. Preservative-free eye drops such as HyloComod improve healing, and prevent symptoms of dry eye syndrome in the EVEITsystem. Compared to EVEIT results of former experiments with benzalconium chloride-preserved eye drops, Optive promoted healing of corneal erosions.
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Affiliation(s)
- N Schrage
- ACTO e.V. An-Institut der medizinischen Fakultät RWTH Aachen, Karlsburgweg 9, 52070 Aachen, Germany.
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Abstract
OBJECTIVE To describe clinical findings in equine subepithelial keratomycosis (SEK). DESIGN Retrospective medical records study. ANIMALS STUDIED Medical records of horses that had subepithelial keratomycosis (SEK) at the University of Florida Veterinary Medical Center from 2007 to 2011 were reviewed. PROCEDURES Data collected from the medical records included signalment, clinical descriptions of ocular lesions, diagnostic techniques, and therapeutic outcomes. RESULTS Twenty-one horses, consisting of three Quarter horse geldings, two Morgan geldings, one Morgan mare, two Arabian mares, three Arabian geldings, two warm blood mares, two warm blood geldings, two Thoroughbred geldings, one Thoroughbred mare, one Appaloosa mare, one Holsteiner gelding, and one Holsteiner mare with SEK were identified. Multifocal punctate and/or geographic patterns of subepithelial opacification were present in all eyes. Intermittent phases of weak fluorescein and/or rose Bengal dye were found in 16 eyes. Clinical signs of iridocyclitis were absent in all eyes. Cytologic confirmation of fungi was found in ten cases, Candida was cultured from one eye, and Aspergillus cultured in three eyes. Nineteen of 21 eyes with SEK resolved when topical antifungal therapy was initiated. Two of the 19 responding eyes recurred and required additional therapy, and two other eyes progressed to ulcerative keratomycosis. CONCLUSIONS This is the first clinical report of a subtle form of keratomycosis in the horse. Subepithelial keratomycosis may be a distinct clinical entity or represent a continuum in the described forms of equine keratomycosis.
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Affiliation(s)
- Dennis E Brooks
- Departments of Large and Small Animal Clinical Sciences, University of Florida, Gainesville, Florida, USA.
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Hillenaar T, van Cleynenbreugel H, Remeijer L. How Normal Is the Transparent Cornea? Effects of Aging on Corneal Morphology. Ophthalmology 2012; 119:241-8. [DOI: 10.1016/j.ophtha.2011.07.041] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 06/28/2011] [Accepted: 07/21/2011] [Indexed: 11/15/2022] Open
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