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Cale M, Roelofs KA, Goldberg RA, Leibowitz S, Glasgow BJ, Rootman DB. Hyperostosis associated with orbital vascular malformation. Orbit 2024; 43:236-239. [PMID: 35850633 DOI: 10.1080/01676830.2022.2101129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Accepted: 07/09/2022] [Indexed: 10/17/2022]
Abstract
A previously healthy adult male presented with a slowly enlarging orbital mass associated with 5 mm of non-pulsatile proptosis. On imaging, a soft tissue lesion with avid contrast enhancement and associated bony hyperostosis was noted. The lesion and hyperostotic bone were surgically debulked, and significant arterial bleeding was noted intraoperatively consistent with an arteriovenous malformation. Histopathologic analysis revealed a vascular malformation with enhanced microvasculature infiltrating the periosteum. While vascular lesions elsewhere in the body can be associated with skeletal changes, bony hyperostosis is a rare feature of orbital vascular malformations.
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Affiliation(s)
- Mario Cale
- Division of Orbital and Ophthalmic Plastic Surgery, Jules Stein Eye Institute, University of California, Los Angeles, California, USA
| | - Kelsey A Roelofs
- Division of Orbital and Ophthalmic Plastic Surgery, Jules Stein Eye Institute, University of California, Los Angeles, California, USA
| | - Robert A Goldberg
- Division of Orbital and Ophthalmic Plastic Surgery, Jules Stein Eye Institute, University of California, Los Angeles, California, USA
| | - Steven Leibowitz
- Division of Orbital and Ophthalmic Plastic Surgery, Jules Stein Eye Institute, University of California, Los Angeles, California, USA
| | - Ben J Glasgow
- Departments of Ophthalmology and Pathology and Laboratory Medicine, Jules Stein Eye Institute, University of California, Los Angeles, California, USA
| | - Daniel B Rootman
- Division of Orbital and Ophthalmic Plastic Surgery, Jules Stein Eye Institute, University of California, Los Angeles, California, USA
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Oh AJ, Goldberg RA, Glasgow BJ. Dedifferentiated liposarcoma of the orbit. Am J Ophthalmol Case Rep 2024; 33:101980. [PMID: 38261879 PMCID: PMC10794919 DOI: 10.1016/j.ajoc.2023.101980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 07/31/2023] [Accepted: 12/20/2023] [Indexed: 01/25/2024] Open
Abstract
Purpose To present a rare case of dedifferentiated liposarcoma of the orbit. Observations A 61-year-old male complained of left-sided proptosis, diplopia, and limited ocular motility for two years. Biopsy results at that time were suggestive of an atypical lipomatous neoplasm. Ten years later, he presented with increase in size of the mass and worsening of his symptoms. Imaging showed a multi-lobulated mass in the left orbit involving the intraconal, medial, and anterior orbit. Decompression and orbitotomy with biopsy were performed to debulk the mass. Pathology showed a low-grade well-differentiated liposarcoma and the patient was monitored thereafter annually. Eight years later, he complained of persistent proptosis and mass effect from the tumor resulting in ptosis and diplopia and underwent orbital exenteration. Histopathological analysis of the exenterated orbit revealed a focal area of dedifferentiated liposarcoma. Conclusions and importance Dedifferentiation of an orbital mass can occur as a late complication years after the diagnosis of well-differentiated liposarcoma. Compared to the previously published cases of orbital liposarcoma, this presentation shows a prolonged timeline prior to dedifferentiation (18 years after initial diagnosis). Symptoms of growth or invasive features could indicate dedifferentiation and should warrant a biopsy.
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Affiliation(s)
- Angela J. Oh
- Departments of Ophthalmology, Jules Stein Eye Institute, University of California, Los Angeles, CA, USA
| | - Robert A. Goldberg
- Departments of Ophthalmology, Jules Stein Eye Institute, University of California, Los Angeles, CA, USA
| | - Ben J. Glasgow
- Departments of Ophthalmology, Jules Stein Eye Institute, University of California, Los Angeles, CA, USA
- Pathology & Laboratory Medicine, Jules Stein Eye Institute, University of California, Los Angeles, CA, USA
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3
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Diep BL, Glasgow BJ, Bert BB. Remission of Ocular Surface Squamous Neoplasia. Ophthalmology 2023:S0161-6420(23)00845-X. [PMID: 38108681 DOI: 10.1016/j.ophtha.2023.11.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/26/2023] [Accepted: 11/13/2023] [Indexed: 12/19/2023] Open
Affiliation(s)
- Brian L Diep
- University of California Riverside School of Medicine, Riverside, California
| | - Ben J Glasgow
- Department of Pathology & Laboratory Medicine, UCLA, Los Angeles, California; Department of Ophthalmology, David Geffen School of Medicine UCLA, Los Angeles, California; Doheny and Stein Eye Institutes, Los Angeles, California
| | - Benjamin B Bert
- Department of Ophthalmology, David Geffen School of Medicine UCLA, Los Angeles, California; Doheny and Stein Eye Institutes, Los Angeles, California
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Oh AJ, Glasgow BJ. Dendritic Melanocytic Hyperplasia in Pterygia: A Potential Source of Diagnostic Confusion with Primary Acquired Melanosis. Ocul Oncol Pathol 2023; 9:48-55. [PMID: 38376097 PMCID: PMC10821784 DOI: 10.1159/000530514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 03/27/2023] [Indexed: 02/21/2024] Open
Abstract
Introduction The aim of this study was to report the nearly ubiquitous prevalence of melanocytic hyperplasia in benign pterygia/pingueculae and establish that the entity is insufficiently recognized. Methods This is a retrospective immunohistochemical pathology case series of 30 consecutive pterygia/pingueculae samples selected from an ophthalmic pathology database at a single institution. Histopathologic and immunohistochemistry analyses with anti-SOX-10 and anti-MART-1 antibodies were used for identifying melanocytes. The number of squamous cells intervening between melanocytes was determined. Results The frequency of dendritic melanocytes was found to meet the criteria for dendritic melanocytic hyperplasia in 29 of 30 pterygia/pingueculae samples using specific antibodies. Melanocytes were found in several patterns: diffuse (28%), multifocal (28%), and focal (44%). In each case, the melanocytes were distributed as single melanocytes at the base; clusters of melanocytes were seen in 17% of samples. There were an average of about two intervening epithelial cells between melanocytes at the base. Conclusion When diagnosed with immunohistochemistry, dendritic melanocytic hyperplasia is nearly ubiquitous in pterygia and pingueculae. Melanocytic hyperplasia may have a distribution that includes nests and single melanocytes above the basal layer, which can be confused with forms of primary acquired melanosis. It is important for pathologists to recognize these lesions as a distinct benign clinicopathologic entity.
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Affiliation(s)
- Angela J. Oh
- Departments of Ophthalmology, Los Angeles, CA, USA
| | - Ben J. Glasgow
- Departments of Ophthalmology, Los Angeles, CA, USA
- Pathology and Laboratory Medicine, Jules Stein Eye Institute, University of California, Los Angeles, CA, USA
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Abstract
A 70-year-old male presented with diplopia and painless proptosis of the left eye for 5 months. Examination showed 6 mm of axial proptosis and restriction of supraduction, abduction and adduction, and mild limitation of infraduction of the left eye. Magnetic resonance imaging demonstrated a large, moderately well-circumscribed intraconal mass in the left lateral orbit, and excisional biopsy was performed. Histopathologic features of mixed fibrous and myxoid areas in a whorl-like pattern and immunohistochemical staining for MUC4 confirmed the diagnosis of low-grade fibromyxoid sarcoma (LGFMS). Next-generation sequencing revealed genetic fusion of EWSR1-CREB3L1. LGFMS is an extremely rare neoplasm with only two prior documented cases of orbital involvement. Here, we report the third case of orbital LGFMS.
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Affiliation(s)
- Angela J Oh
- Division of Orbital and Ophthalmic Plastic Surgery, Jules Stein Eye Institute, University of California, Los Angeles, California, USA
| | - Pallavi Singh
- Division of Orbital and Ophthalmic Plastic Surgery, Jules Stein Eye Institute, University of California, Los Angeles, California, USA
| | - Nathan Pirakitikulr
- Division of Orbital and Ophthalmic Plastic Surgery, Jules Stein Eye Institute, University of California, Los Angeles, California, USA
| | - Kelsey Roelofs
- Division of Orbital and Ophthalmic Plastic Surgery, Jules Stein Eye Institute, University of California, Los Angeles, California, USA
| | - Ben J Glasgow
- Division of Ophthalmic Pathology, Jules Stein Eye Institute, and Department of Pathology and Laboratory Medicine, University of California, Los Angeles, California, USA
| | - Daniel B Rootman
- Division of Orbital and Ophthalmic Plastic Surgery, Jules Stein Eye Institute, University of California, Los Angeles, California, USA
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Abstract
Tear lipocalin is a primate protein that was recognized as a lipocalin from the homology of the primary sequence. The protein is most concentrated in tears and produced by lacrimal glands. Tear lipocalin is also produced in the tongue, pituitary, prostate, and the tracheobronchial tree. Tear lipocalin has been assigned a multitude of functions. The functions of tear lipocalin are inexorably linked to structural characteristics that are often shared by the lipocalin family. These characteristics result in the binding and or transport of a wide range of small hydrophobic molecules. The cavity of tear lipocalin is formed by eight strands (A-H) that are arranged in a β-barrel and are joined by loops between the β-strands. Recently, studies of the solution structure of tear lipocalin have unveiled new structural features such as cation-π interactions, which are extant throughout the lipocalin family. Lipocalin has many unique features that affect ligand specificity. These include a capacious and a flexible cavity with mobile and short overhanging loops. Specific features that confer promiscuity for ligand binding in tear lipocalin will be analyzed. The functions of tear lipocalin include the following: antimicrobial activities, scavenger of toxic and tear disruptive compounds, endonuclease activity, and inhibition of cysteine proteases. In addition, tear lipocalin binds and may modulate lipids in the tears. Such actions support roles as an acceptor for phospholipid transfer protein, heteropolymer formation to alter viscosity, and tear surface interactions. The promiscuous lipid-binding properties of tear lipocalin have created opportunities for its use as a drug carrier. Mutant analogs have been created to bind other molecules such as vascular endothelial growth factor for medicinal use. Tear lipocalin has been touted as a useful biomarker for several diseases including breast cancer, chronic obstructive pulmonary disease, diabetic retinopathy, and keratoconus. The functional possibilities of tear lipocalin dramatically expanded when a putative receptor, lipocalin-interacting membrane receptor was identified. However, opposing studies claim that lipocalin-interacting membrane receptor is not specific for lipocalin. A recent study even suggests a different function for the membrane protein. This controversy will be reviewed in light of gene expression data, which suggest that tear lipocalin has a different tissue distribution than the putative receptor. But the data show lipocalin-interacting membrane receptor is expressed on ocular surface epithelium and that a receptor function here would be rational.
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Affiliation(s)
- Ben J. Glasgow
- Departments of Ophthalmology, Pathology and Laboratory Medicine, Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA, United States
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7
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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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Affiliation(s)
- Ben J Glasgow
- David Geffen School of Medicine at UCLA, Jules Stein Eye Institute, Los Angeles, California, United States. E-mail:
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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10
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Glasgow BJ, Abduragimov AR. Methods toward simplification of time resolved fluorescence anisotropy in proteins labeled with NBD (4-chloro-7-nitrobenzofurazan) adducts. MethodsX 2019; 6:998-1008. [PMID: 31080764 PMCID: PMC6506467 DOI: 10.1016/j.mex.2019.04.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 04/24/2019] [Indexed: 11/25/2022] Open
Abstract
The analysis of time resolved fluorescence anisotropy for NBD tagged proteins is difficult when multiple exponential components arise from heterogeneous amino acid fluorescent adducts. Two approaches were taken toward simplification. First, N terminal selective labeling of tear lipocalin with NBD-Cl was attempted at pH 7.0. While lysines were predominantly labeled at pH 8.0, selective N terminal labeling was attained at neutral pH. Second, fluorescence anisotropic decay analysis was simplified to recover only the rotational correlation time of the protein not the side chain. The boundaries for analysis of anisotropic decays were limited to the longer lifetimes. A modified tail fit enabled fitting the anisotropic decay to a single exponential. The correlation time for tear lipocalin matched published values. Additionally, a method for normalization of acquisition times of vertically (VV) and horizontally (VH) polarized fluorescence emission decays is presented for time-resolved anisotropy. Here it is applied to Picoharp software (Picoquant, Berlin). Picoharp software is programmed with an automatic stop at unequal acquisition times if the fluorescent counts exceeds a default. The method adjusts the intensity decays to the same acquisition time and is applicable to all time-resolved anisotropic decay data collected with time-correlated photon counting. NBD labeling at pH 7.0 was not selective for N terminus of LCN1. Constraints for range simplifies fittings of anisotropic decays. Different acquisition times for decays can be normalized to facilitate fitting in data obtained by Picoharp.
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Affiliation(s)
- Ben J Glasgow
- Departments of Ophthalmology, Pathology and Laboratory Medicine, Jules Stein Eye Institute, University of California, 100 Stein Plaza Rm. BH 623, Los Angeles, CA 90095, United States
| | - Adil R Abduragimov
- Departments of Ophthalmology, Pathology and Laboratory Medicine, Jules Stein Eye Institute, University of California, 100 Stein Plaza Rm. BH 623, Los Angeles, CA 90095, United States
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11
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Ali MH, Pineles SL, Velez FG, Tandon AK, Glasgow BJ. Pathologic Study of Supernumerary Orbital Band in Type I Duane Syndrome. Ocul Oncol Pathol 2019; 5:305-311. [PMID: 31559240 DOI: 10.1159/000496689] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 01/04/2019] [Indexed: 11/19/2022] Open
Abstract
Background/Aims Accessory orbital bands are relatively rare and very few reports detail histopathology. Cases in the literature describe the composition of the bands as muscular and/or fibrous. The composition of the supernumerary band lying deep in the medial rectus muscle in a patient with type I Duane syndrome was investigated. Methods Histochemical stains were used in conjunction with polarized light for differentiating compressed collagen from muscle. Immunohistochemistry was used for verification of the presence of muscle. Results Compressed collagen appeared red using Masson trichrome staining. Collagen was positively identified by illumination with polarized light on several stains including the underutilized Sirius red dye. Conclusions The findings of dense collagen fibers in the fibrotic band with focal striated muscle correlated with the restrictive strabismus. In concert with other cases in the literature, it is proposed that the fibrous bands are generally associated with restrictive strabismus. Bands that are muscular may or may not be associated with strabismus. Special techniques are needed to positively identify compressed collagen.
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Affiliation(s)
- Muhammad Hassaan Ali
- Stein Eye Institute, Departments of Ophthalmology and Pathology and Laboratory Medicine, UCLA, Los Angeles, California, USA
| | - Stacy L Pineles
- Stein Eye Institute, Departments of Ophthalmology and Pathology and Laboratory Medicine, UCLA, Los Angeles, California, USA
| | - Federico G Velez
- Stein Eye Institute, Departments of Ophthalmology and Pathology and Laboratory Medicine, UCLA, Los Angeles, California, USA.,Department of Ophthalmology, Weill Cornell Medical College, New York, New York, USA.,Department of Ophthalmology, Duke University, Durham, North Carolina, USA
| | - Anika K Tandon
- Stein Eye Institute, Departments of Ophthalmology and Pathology and Laboratory Medicine, UCLA, Los Angeles, California, USA.,Doheny Eye Institute, Department of Ophthalmology, UCLA, Los Angeles, California, USA
| | - Ben J Glasgow
- Stein Eye Institute, Departments of Ophthalmology and Pathology and Laboratory Medicine, UCLA, Los Angeles, California, USA
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Glasgow BJ, Abduragimov AR. Ligand binding complexes in lipocalins: Underestimation of the stoichiometry parameter (n). Biochim Biophys Acta Proteins Proteom 2018; 1866:1001-1007. [PMID: 30037780 PMCID: PMC6481938 DOI: 10.1016/j.bbapap.2018.07.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Revised: 06/15/2018] [Accepted: 07/03/2018] [Indexed: 11/18/2022]
Abstract
The stoichiometry of a ligand binding reaction to a protein is given by a parameter (n). The value of this parameter may indicate the presence of protein monomer or dimers in the binding complex. Members of the lipocalin superfamily show variation in the stoichiometry of binding to ligands. In some cases the stoichiometry parameter (n) has been variously reported for the same protein as mono- and multimerization of the complex. Prime examples include retinol binding protein, β lactoglobulin and tear lipocalin, also called lipocalin-1(LCN1). Recent work demonstrated the stoichiometric ratio for ceramide:tear lipocalin varied (range n = 0.3-0.75) by several different methods. The structure of ceramide raises the intriguing possibility of a lipocalin dimer complex with each lipocalin molecule attached to one of the two alkyl chains of ceramide. The stoichiometry of the ceramide-tear lipocalin binding complex was explored in detail using size exclusion chromatography and time resolved fluorescence anisotropy. Both methods showed consistent results that tear lipocalin remains monomeric when bound to ceramide. Delipidation experiments suggest the most likely explanation is that the low 'n' values result from prior occupancy of the binding sites by native ligands. Lipocalins such as tear lipocalin that have numerous binding partners are particularly prone to an underestimated apparent stoichiometry parameter.
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Affiliation(s)
- Ben J Glasgow
- Departments of Ophthalmology, Pathology and Laboratory Medicine, Jules Stein Eye Institute, University of California, Los Angeles, 100 Stein Plaza Rm. BH 623, Los Angeles, CA 90095, United States.
| | - Adil R Abduragimov
- Departments of Ophthalmology, Pathology and Laboratory Medicine, Jules Stein Eye Institute, University of California, Los Angeles, 100 Stein Plaza Rm. BH 623, Los Angeles, CA 90095, United States
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Abstract
A 55-year-old man presented with unilateral orbital inflammation and no light perception vision. Imaging revealed infiltrative enhancement of the optic nerve, orbit, and intracranial tissue. The case was suspicious for invasive fungal disease, but ultimate workup and orbital biopsy revealed granulomatosis with polyangiitis. The patient's inflammation resolved with corticosteroid and rituximab therapy. Granulomatosis with polyangiitis is a systemic vasculitis that can mimic a number of orbital pathologies.
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Affiliation(s)
- David Xu
- a Stein Eye Institute, University of California , Los Angeles , CA , USA
| | - Shawn R Lin
- a Stein Eye Institute, University of California , Los Angeles , CA , USA
| | - Laura Bonelli
- a Stein Eye Institute, University of California , Los Angeles , CA , USA
| | - Ben J Glasgow
- a Stein Eye Institute, University of California , Los Angeles , CA , USA
| | - Robert A Goldberg
- a Stein Eye Institute, University of California , Los Angeles , CA , USA
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Glasgow BJ, Abduragimov AR. Ligand binding studies by high speed centrifugal precipitation and linear spectral summation using ultraviolet-visible absorption spectroscopy. MethodsX 2018; 5:345-351. [PMID: 30050754 PMCID: PMC6058075 DOI: 10.1016/j.mex.2018.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 04/12/2018] [Indexed: 11/30/2022] Open
Abstract
In ligand-protein binding experiments the major challenge is to separate bound from free ligand. Equilibrium and gel filtration separation techniques are often hampered by competition for the ligand and non-specific binding. Biophysical assays have attempted to circumvent this problem using titration calorimetry and spectroscopic methods. However, insoluble ligands require solvents that can overwhelm the discernible enthalpic changes of the protein and ligands. Spectroscopic methods are effective but may suffer from insensitivity (NMR) or the need for a lipid analog e.g., fluorescence and electron paramagnetic resonance. Our purpose is to compare the standard fluorescence assay to a technique we call high speed centrifugal precipitation. High speed centrifugal precipitation is suited to ligands that are insoluble in aqueous. The method permits separation of insoluble free ligand from that bound to the protein. The concentration of the each fraction can be precisely measured by absorbance spectrophotometry. A second technique, linear spectral summation has been published for protein-ligand associations using fluorescence of labeled ligands [1]. Here, the method is altered for use with ultraviolet-visible (UV-Vis) absorption spectroscopy. If the ligand complex shows a shift in the peak absorption of >8 nm, the bound and free concentrations can be measured simultaneously. The composite spectra of the samples are fit by linearly scaling UV-Vis absorption spectra of pure bound and free components at each point. •Ligand- protein binding kinetics is accessible with an ordinary spectrophotometer.•Concentrations are accurately measured from molar extinction coefficients.•The methods are ideal for lipid ligands that show absorption spectral peaks shifts in the bound and free states and/or are insoluble.
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Affiliation(s)
- Ben J Glasgow
- UCLA Departments of Pathology and Ophthalmology, Jules Stein Eye Institute, United States
| | - Adil R Abduragimov
- UCLA Departments of Pathology and Ophthalmology, Jules Stein Eye Institute, United States
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15
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Glasgow BJ, Abduragimov AR. Data on Orphan tear lipid analogs, synthesis and binding to tear lipocalin. Data Brief 2018; 18:999-1004. [PMID: 29900267 PMCID: PMC5996719 DOI: 10.1016/j.dib.2018.03.102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Accepted: 03/21/2018] [Indexed: 11/30/2022] Open
Abstract
Data found in this article include the structures of the orphan tear lipids and their analogs that are binding candidates to tear lipocalin, the mass spectrum of products of collision induced dissociation of putative synthesized compounds of synthesized (O-oleoyl)-16 hydroxypalmitic acid. These data and analyses support the research article "Interaction of ceramides and tear lipocalin" Glasgow et al. (2018) [1].
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Affiliation(s)
- Ben J Glasgow
- Departments of Ophthalmology, Pathology and Laboratory Medicine, Jules Stein Eye Institute, UCLA, United States
| | - Adil R Abduragimov
- Departments of Ophthalmology, Pathology and Laboratory Medicine, Jules Stein Eye Institute, UCLA, United States
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16
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Glasgow BJ, McCannel TA. Correlation of Immunocytochemistry of BRCA1-associated Protein-1 (BAP1) With Other Prognostic Markers in Uveal Melanoma. Am J Ophthalmol 2018. [PMID: 29530782 DOI: 10.1016/j.ajo.2018.03.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE Prior studies have shown that nuclear reactivity for BRCA1-associated protein-1 (BAP1) yields prognostic information for paraffin-embedded uveal melanomas. Lacking are immunocytochemical studies of BAP1 on fine needle aspiration biopsies of uveal melanoma that correlate with prognosis or other markers of prognosis. Our purpose was to fill this gap. DESIGN Experimental laboratory study. METHODS Fine needle aspiration biopsies were performed prospectively on 113 patients with uveal melanomas, garnering limited subsets of cases for comparison. Agreement between immunocytochemistry for BAP1 nuclear staining vs chromosome 3 ploidy analysis and gene expression profiling was assessed by 2 × 2 contingency table analysis. RESULTS The presence or absence of suppression of nuclear expression of BAP1 was strongly associated (73%, P = .000002) with monosomy and disomy chromosome 3, respectively. BAP1 nuclear expression was also correlated with gene expression profiling. Chromosome 3 ploidy analysis correlated with gene expression profiles. CONCLUSION When adequate material is obtained, immunocytology using BAP1 is a potentially informative tool for prognostication of uveal melanoma.
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Glasgow BJ, Abduragimov AR. Interaction of ceramides and tear lipocalin. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1863:399-408. [PMID: 29331331 PMCID: PMC5835416 DOI: 10.1016/j.bbalip.2018.01.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 12/19/2017] [Accepted: 01/06/2018] [Indexed: 10/18/2022]
Abstract
The distribution of lipids in tears is critical to their function. Lipids in human tears may retard evaporation by forming a surface barrier at the air interface. Lipids complexed with the major lipid binding protein in tears, tear lipocalin, reside in the bulk (aqueous) and may have functions unrelated to the surface. Many new lipids species have been revealed through recent mass spectrometric studies. Their association with lipid binding proteins has not been studied. Squalene, (O-acyl) omega-hydroxy fatty acids (OAHFA) and ceramides are examples. Even well-known lipids such as wax and cholesteryl esters are only presumed to be unbound because extracts of protein fractions of tears were devoid of these lipids. Our purpose was to determine by direct binding assays if the aforementioned lipids can bind tear lipocalin. Lipids were screened for ability to displace DAUDA from tear lipocalin in a fluorescence displacement assay. Di- and tri-glycerides, squalene, OAHFA, wax and cholesterol esters did not displace DAUDA from tear lipocalin. However, ceramides displaced DAUDA. Apparent dissociation constants for ceramide-tear lipocalin complexes using fluorescent analogs were measured consistently in the submicromolar range with 3 methods, linear spectral summation, high speed centrifugal precipitation and standard fluorescence assays. At the relatively small concentrations in tears, all ceramides were complexed to tear lipocalin. The lack of binding of di- and tri-glycerides, squalene, OAHFA, as well as wax and cholesterol esters to tear lipocalin is consonant with residence of these lipids near the air interface.
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Affiliation(s)
- Ben J Glasgow
- Departments of Ophthalmology, Pathology and Laboratory Medicine, Jules Stein Eye Institute, University of California, Los Angeles, 100 Stein Plaza Rm. BH 623, Los Angeles, CA 90095, United States.
| | - Adil R Abduragimov
- Departments of Ophthalmology, Pathology and Laboratory Medicine, Jules Stein Eye Institute, University of California, Los Angeles, 100 Stein Plaza Rm. BH 623, Los Angeles, CA 90095, United States
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18
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Abstract
Periocular infection is a rare complication of strabismus surgery. We describe a case of necrotizing Tenon's capsule infection after uncomplicated strabismus surgery in a boy with Down syndrome and blepharitis. Pathologic diagnosis was severe acute necrotizing inflammation with Gram positive coccal forms. Resolution of infection occurred after surgical debridement and intravenous and topical antibiotics. Work-up revealed lymphopenia related to Down syndrome. Patients with Down syndrome may have risk factors for postoperative infection including blepharitis and immunologic abnormalities.
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Affiliation(s)
- Melinda Y Chang
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles; Doheny Eye Institute, University of California, Los Angeles
| | - Wenjing Liu
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles; Doheny Eye Institute, University of California, Los Angeles
| | - Ben J Glasgow
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles; Doheny Eye Institute, University of California, Los Angeles
| | - Sherwin J Isenberg
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles; Doheny Eye Institute, University of California, Los Angeles
| | - Federico G Velez
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles; Doheny Eye Institute, University of California, Los Angeles; Olive View-UCLA Medical Center, University of California, Los Angeles; Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles.
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19
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Kuan EC, Tajudeen BA, Welch KC, Chandra RK, Glasgow BJ, Suh JD. Aggressive necrotizing pseudomonal sinonasal infections. Int Forum Allergy Rhinol 2017; 7:910-915. [PMID: 28707783 DOI: 10.1002/alr.21981] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 05/16/2017] [Accepted: 06/06/2017] [Indexed: 11/06/2022]
Abstract
BACKGROUND Pseudomonas aeruginosa is a gram-negative bacterium frequently implicated in recalcitrant sinonasal infections, especially in immunocompromised hosts. We report 6 cases of rapidly progressive pseudomonal acute rhinosinusitis producing tissue necrosis and, in certain cases, cranial nerve palsies. METHODS Retrospective review of 6 patients with aggressive necrotizing sinonasal infections treated at 4 tertiary academic medical centers with sinonasal cultures growing P. aeruginosa in the absence of other pathology. RESULTS A total of 6 patients were identified. In all cases, there was tissue necrosis that appeared to mimic an invasive process such as mucormycosis, prompting urgent surgical intervention. Pathologic analysis revealed fibropurulent exudates in backgrounds of positive P. aeruginosa cultures without evidence of invasive fungal organisms or malignancy. Four of the 6 patients presented with cranial nerve palsies, with 3 patients having vision changes and 3 complaining of trigeminal neuropathy. Four of 6 patients improved clinically over time after surgery and antibiotic therapy; 1 remains in follow-up without complete improvement and 1 has succumbed to other causes. CONCLUSION P. aeruginosa is a tenacious organism that is frequently associated with severe, recalcitrant sinonasal infections. We report the first case series of necrotizing sinonasal infections caused by this organism, and illustrate that, in rare cases, P. aeruginosa may mimic and behave like life-threatening conditions such as fulminant invasive fungal sinusitis or malignancy.
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Affiliation(s)
- Edward C Kuan
- Department of Head and Neck Surgery, University of California, Los Angeles (UCLA), Los Angeles, CA
| | - Bobby A Tajudeen
- Department of Otolaryngology-Head and Neck Surgery, Rush University Medical Center, Chicago, IL
| | - Kevin C Welch
- Department of Otolaryngology-Head and Neck Surgery, Northwestern University Medical Center, Chicago, IL
| | - Rakesh K Chandra
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN
| | - Ben J Glasgow
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA.,Department of Ophthalmology, University of California, Los Angeles (UCLA), Los Angeles, CA
| | - Jeffrey D Suh
- Department of Head and Neck Surgery, University of California, Los Angeles (UCLA), Los Angeles, CA
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20
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Glasgow BJ. Conventional fluorescence microscopy below the diffraction limit with simultaneous capture of two fluorophores in DNA origami. Proc SPIE Int Soc Opt Eng 2016; 9714. [PMID: 27307653 DOI: 10.1117/12.2211074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A conventional fluorescence microscope was previously constructed for simultaneous imaging of two colors to gain subdiffraction localization. The system is predicated on color separation of overlapping Airy discs, construction of matrices of Cartesian coordinates to determine locations as well as centers of the point spread functions of fluorophores. Quantum dots that are separated by as little as 10 nm were resolved in the x-y coordinates. Inter-fluorophore distances that vary by 10 nm could also be distinguished. Quantum dots are bright point light source emitters that excite with a single laser and can serve as a label for many biomolecules. Here, alterations in the method are described to test the ability to resolve Atto 488 and Atto 647 dyes attached to DNA origami at ~40 nm spacing intervals. Dual laser excitation is used in tandem with multi-wavelength bandpass filters. Notwithstanding challenges from reduced intensity in Atto labeled DNA origami helical bundles compared to quantum dots, preliminary data show a mean inter-fluorophore distance of 56 nm with a range (14-148 nm). The range closely matches published results with DNA origami with other methods of subdiffraction microscopy. Sub-diffraction simultaneous two-color imaging fluorescence microscopy acronymically christened (SSTIFM) is a simple, readily accessible, technique for measurement of inter-fluorophore distances in compartments less than 40 nm. Preliminary results with so called nanorulers are encouraging for use with other biomolecules.
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Affiliation(s)
- Ben J Glasgow
- Departments of Ophthalmology, Pathology and Laboratory Medicine, Jules Stein Eye Institute, University of California, Los Angeles, 100 Stein Plaza Rm. BH 623, Los Angeles, CA 90095
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21
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Glasgow BJ, Ma L. Simultaneous two color image capture for sub-diffraction localization fluorescence microscopy. Micron 2015; 80:14-9. [PMID: 26409111 DOI: 10.1016/j.micron.2015.09.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 09/09/2015] [Accepted: 09/09/2015] [Indexed: 11/19/2022]
Abstract
A sub-diffraction limit fluorescence localization microscope was constructed using a standard cooled 1.4 mega-pixel fluorescence charge-coupled device (CCD) camera to simultaneously resolve closely adjacent paired quantum dots on a flat surface with emissions of 540 and 630 nm. The images of the overlapping Airy discs were analyzed to determine the center of the point spread function after noise reduction using Fourier transformation analysis. The Cartesian coordinates of the centers of the point spread functions were compared in serial images. Histograms constructed from serial images fit well to Gaussian functions for resolving two quantum dots separated by as little as 10nm in the x-y coordinates. Statistical analysis of multiple pairs validated discrimination of inter-fluorophore distances that vary by 10nm. The method is simple and developed for x-y resolution of dilute fluorophores on a flat surface, not serial z sectioning.
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Affiliation(s)
- Ben J Glasgow
- Departments of Ophthalmology, Pathology and Laboratory Medicine, Jules Stein Eye Institute, University of California, Los Angeles, 100 Stein Plaza Rm. BH 623, Los Angeles, CA 90095, USA.
| | - Lie Ma
- Departments of Ophthalmology, Pathology and Laboratory Medicine, Jules Stein Eye Institute, University of California, Los Angeles, 100 Stein Plaza Rm. BH 623, Los Angeles, CA 90095, USA
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22
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Klufas MA, Itty S, McCannel CA, Glasgow BJ, Moreno C, McCannel TA. Variable Results for Uveal Melanoma–Specific Gene Expression Profile Prognostic Test in Choroidal Metastasis. JAMA Ophthalmol 2015; 133:1073-6. [DOI: 10.1001/jamaophthalmol.2015.1790] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Michael A. Klufas
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles
| | - Sujit Itty
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles
| | - Colin A. McCannel
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles
| | - Ben J. Glasgow
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles
| | - Christian Moreno
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles
| | - Tara A. McCannel
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles
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23
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Gasymov OK, Abduragimov AR, Glasgow BJ. Exploring protein solution structure: Second moments of fluorescent spectra report heterogeneity of tryptophan rotamers. Spectrochim Acta A Mol Biomol Spectrosc 2015; 150:909-920. [PMID: 26119357 PMCID: PMC4550534 DOI: 10.1016/j.saa.2015.06.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 03/11/2015] [Accepted: 06/15/2015] [Indexed: 06/04/2023]
Abstract
Trp fluorescent spectra appear as a log-normal function but are usually analyzed with λmax, full width at half maximum, and the first moment of incomplete spectra. Log-normal analyses have successfully separated fluorescence contributions from some multi-Trp proteins but deviations were observed in single Trp proteins. The possibility that disparate rotamer environments might account for these deviations was explored by moment spectral analysis of single Trp mutants spanning the sequence of tear lipocalin as a model. The analysis required full width Trp spectra. Composite spectra were constructed using log-normal analysis to derive the inaccessible blue edge, and the experimentally obtained spectra for the remainder. First moments of the composite spectra reflected the site-resolved secondary structure. Second moments were most sensitive for spectral deviations. A novel parameter, derived from the difference of the second moments of composite and simulated log-normal spectra correlated with known multiple heterogeneous rotamer conformations. Buried and restricted side chains showed the most heterogeneity. Analyses applied to other proteins further validated the method. The rotamer heterogeneity values could be rationalized by known conformational properties of Trp residues and the distribution of nearby charged groups according to the internal Stark effect. Spectral heterogeneity fits the rotamer model but does not preclude other contributing factors. Spectral moment analysis of full width Trp emission spectra is accessible to most laboratories. The calculations are informative of protein structure and can be adapted to study dynamic processes.
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Affiliation(s)
- Oktay K Gasymov
- Departments of Pathology and Ophthalmology and Jules Stein Eye Institute, University California at Los Angeles, CA 90095, United States.
| | - Adil R Abduragimov
- Departments of Pathology and Ophthalmology and Jules Stein Eye Institute, University California at Los Angeles, CA 90095, United States.
| | - Ben J Glasgow
- Departments of Pathology and Ophthalmology and Jules Stein Eye Institute, University California at Los Angeles, CA 90095, United States.
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24
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Gasymov OK, Abduragimov AR, Glasgow BJ. Double tryptophan exciton probe to gauge proximal side chains in proteins: augmentation at low temperature. J Phys Chem B 2015; 119:3962-8. [PMID: 25693116 DOI: 10.1021/jp512864s] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The circular dichroic (CD) exciton couplet between tryptophans and/or tyrosines offers the potential to probe distances within 10 Å in proteins. The exciton effect has been used with native chromophores in critical positions in a few proteins. Here, site-directed mutagenesis created double tryptophan probes for key sites of a protein (tear lipocalin). For tear lipocalin, the crystal and solution structures are concordant in both apo- and holo-forms. Double tryptophan substitutions were performed at sites that could probe conformation and were likely within 10 Å. Far-UV CD spectra of double Trp mutants were performed with controls that had noninteracting substituted tryptophans. Low temperature (77 K) was tested for augmentation of the exciton signal. Exciton coupling appeared with tryptophan substitutions at positions within loop A-B (28 and 31, 33), between loop A-B (28) and strand G (103 and 105), as well as between the strands B (35) and C (56). The CD exciton couplet signals were amplified 3-5-fold at 77 K. The results were concordant with close distances in crystal and solution structures. The exciton couplets had functional significance and correctly assigned the holo-conformation. The methodology creates an effective probe to identify proximal amino acids in a variety of motifs.
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Affiliation(s)
- Oktay K Gasymov
- Departments of Pathology and Ophthalmology and Jules Stein Eye Institute, University California at Los Angeles , Los Angeles, California 90095, United States
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25
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Bilgin G, Al-Obailan M, Bonelli L, Glasgow BJ, Vinters HV, Arnold AC. Aggressive Low-Grade Optic Nerve Glioma in Adults. Neuroophthalmology 2014; 38:297-309. [PMID: 27928317 DOI: 10.3109/01658107.2014.966851] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 09/10/2014] [Accepted: 09/10/2014] [Indexed: 11/13/2022] Open
Abstract
Primary optic nerve gliomas are most commonly benign pilocytic astrocytomas (World Health Organization [WHO] Grade I) occurring in childhood and following an indolent course. Malignant optic gliomas occur in adulthood and follow an extremely aggressive course, with rapid infiltration of the chiasm, blindness, and death typically within months. A third category of optic glioma, occurring in adulthood, histopathologically benign (WHO Grade I-II) but following an aggressive course, has been rarely reported. The authors describe clinical and histopathologic features of clinically aggressive but histopathologically benign optic nerve gliomas of adulthood. Retrospective review of cases of biopsy-proven optic nerve glioma in the neuro-ophthalmology division of the Jules Stein Eye Institute from 1990 to 2011 was carried out. Cases following an aggressive course were selected for review of clinical, neuroradiologic, and histopathologic features. Three cases were selected for detailed study. Ages ranged from 31 to 45 years. All were initially diagnosed with optic nerve inflammation or benign neoplasm based on clinical and neuroradiologic features, but all suffered neuroradiologic extension and rapid deterioration of vision in the affected eye to no light perception over 3-8 weeks. Optic nerve biopsies were undertaken for the suspicion of malignancy. Features ranged from WHO Grade I (pilocytic astrocytoma, ganglioglioma) in two cases, to WHO Grade II in one case (diffuse astrocytoma, histopathologically benign, but associated with aggressive features such as high p53 [13-21%] and Ki-67 [40%]). The diffuse astrocytoma case subsequently developed extensive intracranial extension suspicious for malignant transformation. These findings indicate that benign optic nerve glioma in adults may be initially misdiagnosed as inflammation, be clinically aggressive, and require excision to prevent further intracranial involvement.
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Affiliation(s)
- Gorkem Bilgin
- Department of Ophthalmology, Jules Stein Eye Institute
| | | | - Laura Bonelli
- Department of Ophthalmology, Jules Stein Eye Institute
| | - Ben J Glasgow
- Department of Ophthalmology, Jules Stein Eye Institute; Department of Pathology and Laboratory Medicine
| | - Harry V Vinters
- Department of Pathology and Laboratory Medicine; Department of Neurology, David Geffen School of Medicine at University of CaliforniaLos Angeles, CaliforniaUSA
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26
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Staudinger T, Redl B, Glasgow BJ. Antibacterial activity of rifamycins for M. smegmatis with comparison of oxidation and binding to tear lipocalin. Biochim Biophys Acta 2014; 1844:750-8. [PMID: 24530503 PMCID: PMC3992280 DOI: 10.1016/j.bbapap.2014.02.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 01/28/2014] [Accepted: 02/03/2014] [Indexed: 11/19/2022]
Abstract
A mutant of Mycobacterium smegmatis is a potential class I model substitute for Mycobacterium tuberculosis. Because not all of the rifamycins have been tested in this organism, we determined bactericidal profiles for the 6 major rifamycin derivatives. The profiles closely mirrored those established for M. tuberculosis. Rifalazil was confirmed to be the most potent rifamycin. Because the tuberculous granuloma presents a harshly oxidizing environment we explored the effects of oxidation on rifamycins. Mass spectrometry confirmed that three of the six major rifamycins showed autoxidation in the presence of trace metals. Oxidation could be monitored by distinctive changes including isosbestic points in the ultraviolet-visible spectrum. Oxidation of rifamycins abrogated anti-mycobacterial activity in M. smegmatis. Protection from autoxidation was conferred by binding susceptible rifamycins to tear lipocalin, a promiscuous lipophilic protein. Rifalazil was not susceptible to autoxidation but was insoluble in aqueous solution. Solubility was enhanced when complexed to tear lipocalin and was accompanied by a spectral red shift. The positive solvatochromism was consistent with robust molecular interaction and binding. Other rifamycins also formed a complex with lipocalin, albeit to a lesser extent. Protection from oxidation and enhancement of solubility with protein binding may have implications for delivery of select rifamycin derivatives.
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Affiliation(s)
- Tamara Staudinger
- Department of Ophthalmology, Jules Stein Eye Institute, University of California, Los Angeles, 100 Stein Plaza, Rm. B-279, Los Angeles, CA 90095, USA; Department of Pathology and Laboratory Medicine, Jules Stein Eye Institute, University of California, Los Angeles, 100 Stein Plaza, Rm. B-279, Los Angeles, CA 90095, USA; Division of Molecular Biology, Biocenter, Innsbruck Medical University, Innrain 80-82, A-6020 Innsbruck, Austria
| | - Bernhard Redl
- Division of Molecular Biology, Biocenter, Innsbruck Medical University, Innrain 80-82, A-6020 Innsbruck, Austria
| | - Ben J Glasgow
- Department of Ophthalmology, Jules Stein Eye Institute, University of California, Los Angeles, 100 Stein Plaza, Rm. B-279, Los Angeles, CA 90095, USA; Department of Pathology and Laboratory Medicine, Jules Stein Eye Institute, University of California, Los Angeles, 100 Stein Plaza, Rm. B-279, Los Angeles, CA 90095, USA.
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27
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Bui T, Young JW, Frausto RF, Markello TC, Glasgow BJ, Aldave AJ. Hereditary Benign Intraepithelial Dyskeratosis: Report of a Case and Re-examination of the Evidence for Locus Heterogeneity. Ophthalmic Genet 2014; 37:76-80. [PMID: 24555743 DOI: 10.3109/13816810.2014.889169] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Hereditary benign intraepithelial dyskeratosis (HBID) is a rare autosomal-dominant disorder of the conjunctiva and oral mucosa first described in and predominantly affecting descendents of Haliwa-Saponi Native Americans. We report a spontaneous case of histopathologically-confirmed HBID affecting an individual not of Native American ancestry. MATERIALS AND METHODS Report of a case with histopathologic examination of an excised conjunctival specimen as well as molecular and cytogenetic analysis. RESULTS A Caucasian boy with a history of oral lesions and conjunctival injection from birth developed bilateral corneal opacities at age 5 and underwent penetrating keratoplasty, with recurrence of the corneal opacification shortly after surgery. Examination of a conjunctival biopsy specimen revealed features consistent with HBID. Copy number variant (CNV) analysis revealed a de novo 4q35 duplication that overlapped the duplication previously associated with HBID, although no genes were identified in the common interval. NLRP1 gene sequencing failed to reveal a presumed pathogenic variant. CONCLUSIONS HBID may develop de novo in individuals who are not of Native American ancestry. The absence of coding regions in a duplicated region of 4q35 common to both the individual that we report and previously associated with HBID raises questions regarding the significance of this CNV in the pathogenesis of HBID.
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Affiliation(s)
- Tina Bui
- a The Jules Stein Eye Institute, David Geffen School of Medicine at UCLA , Los Angeles , CA , USA and
| | - Jonathan W Young
- a The Jules Stein Eye Institute, David Geffen School of Medicine at UCLA , Los Angeles , CA , USA and
| | - Ricardo F Frausto
- a The Jules Stein Eye Institute, David Geffen School of Medicine at UCLA , Los Angeles , CA , USA and
| | - Thomas C Markello
- b Undiagnosed Diseases Program, Office of Rare Diseases, NIH , Bethesda , MD , USA
| | - Ben J Glasgow
- a The Jules Stein Eye Institute, David Geffen School of Medicine at UCLA , Los Angeles , CA , USA and
| | - Anthony J Aldave
- a The Jules Stein Eye Institute, David Geffen School of Medicine at UCLA , Los Angeles , CA , USA and
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28
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Gasymov OK, Abduragimov AR, Glasgow BJ. Probing tertiary structure of proteins using single Trp mutations with circular dichroism at low temperature. J Phys Chem B 2014; 118:986-95. [PMID: 24404774 PMCID: PMC3983331 DOI: 10.1021/jp4120145] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
![]()
Trp is the most spectroscopically
informative aromatic amino acid
of proteins. However, the near-UV circular dichroism (CD) spectrum
of Trp is complicated because the intensity and sign of 1La and 1Lb bands vary independently.
To resolve vibronic structure and gain site-specific information from
complex spectra, deconvolution was combined with cooling and site-directed
tryptophan substitution. Low temperature near-UV CD was used to probe
the local tertiary structure of a loop and α-helix in tear lipocalin.
Upon cooling, the enhancement of the intensities of the near-UV CD
was not uniform, but depends on the position of Trp in the protein
structure. The most enhanced 1Lb band was observed
for Trp at position 124 in the α-helix segment matching the
known increased conformational mobility during ligand binding. Some
aspects of the CD spectra of W28 and W130 were successfully linked
to specific rotamers of Trp previously obtained from fluorescence
lifetime measurements. The discussion was based on a framework that
the magnitude of the energy differences in local conformations governs
the changes in the CD intensities at low temperature. The Trp CD spectral
classification of Strickland was modified to facilitate the recognition
of pseudo peaks. Near-UV CD spectra harbor abundant information about
the conformation of proteins that site directed Trp CD can report.
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Affiliation(s)
- Oktay K Gasymov
- Departments of Pathology and Ophthalmology and Jules Stein Eye Institute, University California at Los Angeles , California 90095, United States
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29
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Gasymov OK, Abduragimov AR, Glasgow BJ. Effect of short- and long-range interactions on trp rotamer populations determined by site-directed tryptophan fluorescence of tear lipocalin. PLoS One 2013; 8:e78754. [PMID: 24205305 PMCID: PMC3810256 DOI: 10.1371/journal.pone.0078754] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 09/20/2013] [Indexed: 11/25/2022] Open
Abstract
In the lipocalin family, the conserved interaction between the main α-helix and the β-strand H is an ideal model to study protein side chain dynamics. Site-directed tryptophan fluorescence (SDTF) has successfully elucidated tryptophan rotamers at positions along the main alpha helical segment of tear lipocalin (TL). The rotamers assigned by fluorescent lifetimes of Trp residues corroborate the restriction expected based on secondary structure. Steric conflict constrains Trp residues to two (t, g−) of three possible χ1 (t, g−, g+) canonical rotamers. In this study, investigation focused on the interplay between rotamers for a single amino acid position, Trp 130 on the α-helix and amino acids Val 113 and Leu 115 on the H strand, i.e. long range interactions. Trp130 was substituted for Phe by point mutation (F130W). Mutations at positions 113 and 115 with combinations of Gly, Ala, Phe residues alter the rotamer distribution of Trp130. Mutations, which do not distort local structure, retain two rotamers (two lifetimes) populated in varying proportions. Replacement of either long range partner with a small amino acid, V113A or L115A, eliminates the dominance of the t rotamer. However, a mutation that distorts local structure around Trp130 adds a third fluorescence lifetime component. The results indicate that the energetics of long-range interactions with Trp 130 further tune rotamer populations. Diminished interactions, evident in W130G113A115, result in about a 22% increase of α-helix content. The data support a hierarchic model of protein folding. Initially the secondary structure is formed by short-range interactions. TL has non-native α-helix intermediates at this stage. Then, the long-range interactions produce the native fold, in which TL shows α-helix to β-sheet transitions. The SDTF method is a valuable tool to assess long-range interaction energies through rotamer distribution as well as the characterization of low-populated rotameric states of functionally important excited protein states.
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Affiliation(s)
- Oktay K. Gasymov
- Departments of Pathology and Laboratory Medicine and Ophthalmology and Jules Stein Eye Institute, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail: (OG); (BG)
| | - Adil R. Abduragimov
- Departments of Pathology and Laboratory Medicine and Ophthalmology and Jules Stein Eye Institute, University of California Los Angeles, Los Angeles, California, United States of America
| | - Ben J. Glasgow
- Departments of Pathology and Laboratory Medicine and Ophthalmology and Jules Stein Eye Institute, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail: (OG); (BG)
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30
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Gasymov OK, Abduragimov AR, Glasgow BJ. A simple model-free method for direct assessment of fluorescent ligand binding by linear spectral summation. J Fluoresc 2013; 24:231-8. [PMID: 24043458 DOI: 10.1007/s10895-013-1290-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 08/21/2013] [Indexed: 10/26/2022]
Abstract
Fluorescent tagged ligands are commonly used to determine binding to proteins. However, bound and free ligand concentrations are not directly determined. Instead the response in a fluorescent ligand titration experiment is considered to be proportional to the extent of binding and, therefore, the maximum value of binding is scaled to the total protein concentration. Here, a simple model-free method is presented to be performed in two steps. In the first step, normalized bound and free spectra of the ligand are determined. In the second step, these spectra are used to fit composite spectra as the sum of individual components or linear spectral summation. Using linear spectral summation, free and bound 1-Anilinonaphthalene-8-Sulfonic Acid (ANS) fluorescent ligand concentrations are directly calculated to determine ANS binding to tear lipocalin (TL), an archetypical ligand binding protein. Error analysis shows that the parameters that determine bound and free ligand concentrations were recovered with high certainty. The linear spectral summation method is feasible when fluorescence intensity is accompanied by a spectral shift upon protein binding. Computer simulations of the experiments of ANS binding to TL indicate that the method is feasible when the fluorescence spectral shift between bound and free forms of the ligand is just 8 nm. Ligands tagged with environmentally sensitive fluorescent dyes, e.g., dansyl chromophore, are particularly suitable for this method.
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Affiliation(s)
- Oktay K Gasymov
- Departments of Ophthalmology, Pathology and Laboratory Medicine, Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles, CA, 90095, USA,
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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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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Gasymov OK, Abduragimov AR, Glasgow BJ. Tryptophan rotamer distribution revealed for the α-helix in tear lipocalin by site-directed tryptophan fluorescence. J Phys Chem B 2012; 116:13381-8. [PMID: 23088798 DOI: 10.1021/jp309318r] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Rotamer libraries are a valuable tool for protein structure determination, modeling, and design. Site-directed tryptophan fluorescence (SDTF) was used in combination with the rotamer model for the fluorescence intensity decays to solve α-helical conformations of proteins in solution. Single Trp mutations located in an α-helical segment of human tear lipocalin were explored for structure assignment. Along with fluorescence λ(max) values, the rotamer model assignment of fluorescence lifetimes fits the backbone conformation. Typically, Trp fluorescence in proteins shows three lifetimes. However, for the α-helix, two lifetimes assigned to t and g(-) rotamers were satisfactory to describe Trp fluorescence intensity decays. The g(+) rotamer is not feasible in the α-helix due to steric restriction. Trp rotamer distributions obtained by fluorescence were compared with the rotamer library derived from X-ray crystallography data of proteins. The Trp rotamer distributions vary for solvent exposed and buried (tertiary interaction) sites. A new strategy using the rotamer distribution with SDTF (RD-SDTF) removes the limitation of regular SDTF and other labeling techniques, in which site-specific differences, e.g., accessibility, are presumed. The RD-SDTF technique does not rely on environmental differences of side chains and is able to detect α-helical structure where all side chains are exposed to solvent. Potentially, this technique is applicable to various proteins including membrane proteins, which are rich in α-helix motif.
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Affiliation(s)
- Oktay K Gasymov
- Department of Pathology and Jules Stein Eye Institute, University California at Los Angeles, Los Angeles, California 90095, USA.
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Vira D, Pesce J, Glasgow BJ, Lai C, Elashoff D, Abemayor E, John MS. Parotidectomy and neck dissection in the management of conjunctival melanoma: are they necessary? Laryngoscope 2012; 122:2436-41. [PMID: 23007927 DOI: 10.1002/lary.23239] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Revised: 01/09/2012] [Accepted: 01/17/2012] [Indexed: 11/07/2022]
Abstract
OBJECTIVES/HYPOTHESIS The objectives of this study were to review traditional techniques for the management of conjunctival melanoma and assess the need for parotidectomy and neck dissection in the management of conjunctival melanoma. STUDY DESIGN Retrospective review. METHODS This study was a retrospective review conducted in a tertiary academic medical center of patients diagnosed with conjunctival melanoma over a 20-year period RESULTS There were 39 patients diagnosed with conjunctival melanoma identified from January 1990 to December 2010. Follow-up varied from 2 to 201 months (median, 25 months). Of the patients, 16 (41%) had local recurrences at the primary site, two (13%) of whom later presented with parotid disease. One patient with parotid recurrence had a subsequent neck dissection for confirmed metastatic spread. No patient in this series had metastatic cervical disease without initial spread to the parotid. The probability of disease-free survival at 1, 2, and 5 years was 77%, 68%, and 50%, respectively. The probability of parotid free progression at 1, 2, and 5 years was 100%, 96%, and 90%, respectively. CONCLUSIONS Conjunctival melanoma is a rare malignancy traditionally managed with aggressive treatment to optimize local control. The role for staging parotidectomy with or without neck dissection has been heavily debated. Based on our review, parotidectomy only needs to be undertaken when high suspicion for metastatic spread is present, such as a palpable or radiographically evident mass. In addition, without documented parotid disease, neck dissection is not required.
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Affiliation(s)
- Darshni Vira
- Department of Head and Neck Surgery, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, USA.
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Abstract
PURPOSE The purpose of this article was to identify by mass spectrometry phosphocholine lipids in stimulated human tears and determine the molecules bound to tear lipocalin or other proteins. METHODS Tear proteins were separated isocratically from pooled stimulated human tears by gel filtration fast performance liquid chromatography. Separation of tear lipocalin was confirmed by SDS tricine gradient PAGE. Protein fractions were extracted with chloroform/methanol and analyzed with electrospray ionization MS/MS triple quadrupole mass spectrometry in precursor ion scan mode for select leaving groups. For quantification, integrated ion counts were derived from standard curves of authentic compounds of phosphatidylcholine (PC) and phosphatidylserine. RESULTS Linear approximation was possible from integration of the mass spectrometrically obtained ion peaks at 760 Da for the PC standard. Tears contained 194 ng/mL of the major intact PC (34:2), m/z 758.6. Ten other monoisotopic phosphocholines were found in tears. A peak at 703.3 Da was assigned as a sphingomyelin. Four lysophosphatidylcholines (m/z 490-540) accounted for about 80% of the total integrated ion count. The [M+H](+) compound, m/z 496.3, accounted for 60% of the signal intensity. Only the tear lipocalin-bearing fractions showed phosphocholines (104 ng/mL). Although the intact phospholipids bound to tear lipocalin corresponded precisely in mass and relative signal intensity to that found in tears, we did not identify phosphocholines between m/z 490 and 540 in any of the gel-filtration fractions. CONCLUSIONS Phospholipids, predominantly lysophospholipids, are present in tears. The higher mass intact PCs in tears are native ligands of tear lipocalin.
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Affiliation(s)
- Austin W Dean
- Departments of Ophthalmology, Pathology, and Laboratory Medicine, David Geffen School of Medicine at the University of California-Los Angeles, Jules Stein Eye Institute, Los Angeles, CA 90095, USA
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Abstract
The cation-π interaction impacts protein folding, structural stability, specificity, and molecular recognition. Cation-π interactions have been overlooked in the lipocalin family. To fill this gap, these interactions were analyzed in the 113 crystal and solution structures from the lipocalin family. The cation-π interactions link previously identified structurally conserved regions and reveal new motifs, which are beyond the reach of a sequence alignment algorithm. Functional and structural significance of the interactions were tested experimentally in human tear lipocalin (TL). TL, a prominent and promiscuous lipocalin, has a key role in lipid binding at the ocular surface. Ligand binding modulation through the loop AB at the "open" end of the barrel has been erroneously attributed solely to electrostatic interactions. Data revealed that the interloop cation-π interaction in the pair Phe28-Lys108 contributes significantly to stabilize the holo-conformation of the loop AB. Numerous energetically significant and conserved cation-π interactions were uncovered in TL and throughout the lipocalin family. Cation-π interactions, such as the highly conserved Trp17-Arg118 pair in TL, were educed in low temperature experiments of mutants with Trp to Tyr substitutions.
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Affiliation(s)
- Oktay K Gasymov
- Department of Pathology and Jules Stein Eye Institute, University California at Los Angeles, California 90095, USA.
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Mokhtarzadeh M, Casey R, Glasgow BJ. Fluorescein punctate staining traced to superficial corneal epithelial cells by impression cytology and confocal microscopy. Invest Ophthalmol Vis Sci 2011; 52:2127-35. [PMID: 21212176 DOI: 10.1167/iovs.10-6489] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
PURPOSE The basis of fluorescein-associated superficial punctate staining in dry eyes is controversial. Prior explanations include fluorescein pooling in surface erosive defects, intercellular trapping of fluorescein, and intracellular staining in dead cells. In this study, the hypothesis that punctate erosions are individual cells with enhanced fluorescence was tested. METHODS Ten impression cytology membrane materials were compared, to optimize cellular yield in buccal mucosa and cornea. Clinicocytologic correlation of punctate fluorescent spots was performed in four dry eye patients. Individual punctate spots were localized by fiducial marks in photographs, before and after removal with impression membranes, and were traced in fluorescence microscopy and cytologic staining. Two-way contingency table analysis was used to determine the correlation of punctate spots with cells removed by the membrane. Clinicopathologic correlation of punctate spots was performed in 10 corneas removed in dry eye patients by transplantation for concurrent diseases. Punctate fluorescence was tracked in specimens by fiducial marks and epifluorescence. The distribution of fluorescent spots in specific cell layers of the cornea was determined by confocal microscopy. RESULTS Cellular yield was greatest with impressions from polytetrafluoroethylene (PTFE [Teflon]; BioPore; Millipore, Billerica, MA) membrane compared with its closest rival (P = 0.019). Punctate fluorescent spots, most of which disappeared after impression cytology (71%), correlated with cells on the membranes (P = 0.009). The punctate spots were more frequent in the superficial cell layers of the cornea (80%) compared with the deepest two layers (0%) (P < 0.00049). CONCLUSIONS Punctate epithelial erosions correspond to enhanced fluorescence in epithelial cells predominantly in superficial layers of the cornea and would be more aptly named fluorescent epithelial cells (FLECs).
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Gasymov OK, Abduragimov AR, Glasgow BJ. The conserved disulfide bond of human tear lipocalin modulates conformation and lipid binding in a ligand selective manner. Biochim Biophys Acta 2011; 1814:671-83. [PMID: 21466861 DOI: 10.1016/j.bbapap.2011.03.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 02/28/2011] [Accepted: 03/29/2011] [Indexed: 11/26/2022]
Abstract
The primary aim of this study is the elucidation of the mechanism of disulfide induced alteration of ligand binding in human tear lipocalin (TL). Disulfide bonds may act as dynamic scaffolds to regulate conformational changes that alter protein function including receptor-ligand interactions. A single disulfide bond, (Cys61-Cys153), exists in TL that is highly conserved in the lipocalin superfamily. Circular dichroism and fluorescence spectroscopies were applied to investigate the mechanism by which disulfide bond removal effects protein stability, dynamics and ligand binding properties. Although the secondary structure is not altered by disulfide elimination, TL shows decreased stability against urea denaturation. Free energy change (ΔG(0)) decreases from 4.9±0.2 to 2.1±0.3kcal/mol with removal of the disulfide bond. Furthermore, ligand binding properties of TL without the disulfide vary according to the type of ligand. The binding of a bulky ligand, NBD-cholesterol, has a decreased time constant (from 11.8±0.2 to 3.3s). In contrast, the NBD-labeled phospholipid shows a moderate decrease in the time constant for binding, from 33.2±0.2 to 22.2±0.4s. FRET experiments indicate that the hairpin CD is directly involved in modulation of both ligand binding and flexibility of TL. In TL complexed with palmitic acid (PA-TL), the distance between the residues 62 of strand D and 81 of loop EF is decreased by disulfide bond reduction. Consequently, removal of the disulfide bond boosts flexibility of the protein to reach a CD-EF loop distance (24.3Å, between residues 62 and 81), which is not accessible for the protein with an intact disulfide bond (26.2Å). The results suggest that enhanced flexibility of the protein promotes a faster accommodation of the ligand inside the cavity and an energetically favorable ligand-protein complex.
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Affiliation(s)
- Oktay K Gasymov
- Department of Pathology, University of California, Los Angeles, USA.
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Green-Church KB, Butovich I, Willcox M, Borchman D, Paulsen F, Barabino S, Glasgow BJ. The international workshop on meibomian gland dysfunction: report of the subcommittee on tear film lipids and lipid-protein interactions in health and disease. Invest Ophthalmol Vis Sci 2011; 52:1979-93. [PMID: 21450916 DOI: 10.1167/iovs.10-6997d] [Citation(s) in RCA: 222] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Kari B Green-Church
- Department of Molecular and Cellular Biochemistry, Ohio State University, Columbus, Ohio 43210-1280, USA
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Nichols KK, Foulks GN, Bron AJ, Glasgow BJ, Dogru M, Tsubota K, Lemp MA, Sullivan DA. The international workshop on meibomian gland dysfunction: executive summary. Invest Ophthalmol Vis Sci 2011; 52:1922-9. [PMID: 21450913 DOI: 10.1167/iovs.10-6997a] [Citation(s) in RCA: 619] [Impact Index Per Article: 47.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Kelly K Nichols
- College of Optometry, Ohio State University, Columbus, Ohio 43210-1280, USA.
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Thinda S, Sikh PK, Hopp LM, Glasgow BJ. Polycarbonate membrane impression cytology: evidence for fluorescein staining in normal and dry eye corneas. Br J Ophthalmol 2011; 94:406-9. [PMID: 20424211 DOI: 10.1136/bjo.2009.167031] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND/AIMS Corneal impression cytology is usually performed with mixed cellulose ester membranes and a limited array of stains. A method using polycarbonate membrane air-dried preparations led to the discovery of fluorescein staining in cells from patients with and without dry eye disease and a membrane-induced defect that was not due to cell removal. METHODS Impressions after fluorescein installation were performed using polycarbonate and mixed cellulose ester membranes with rapid staining protocols for Diff-Quick as well as haematoxylin and eosin stains. Prior to staining the air-dried material was examined for fluorescence. RESULTS Epithelia of both normal and dry eye corneas retained fluorescence from clinical instillation of fluorescein. Corneal defects created by the polycarbonate membrane could not be explained by membrane-induced cell removal. After rapid staining, polycarbonate membranes revealed less background, dissolved easily prior to coverslip application, but showed lower cellular yield compared with the mixed cellulose membranes. CONCLUSION Polycarbonate membrane impression cytology enables immediate assessment with rapid stains. Topically applied fluorescein penetrates corneal epithelial cells in both normal and dry eye patients. Cells fluoresce on the cytology membranes. The impression-induced defect on the cornea is not due to cell stripping and may represent removal of mucins.
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Affiliation(s)
- Sumeer Thinda
- Jules Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
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Abstract
OBJECTIVE To compare immunohistochemical results of cytokeratin AE1/AE3, the traditional favored marker, with MUC16 and cytokeratin 19 for diagnostic sensitivity and specificity in epithelial downgrowth and control corneas. METHODS Immunohistochemical analysis was performed in 5 cases of epithelial downgrowth and 5 control specimens for MUC16, cytokeratin AE1/AE3, and cytokeratin 19 using the immunoperoxidase method. The mean percentages of reactive cells on the epithelium and endothelium were compared for each antibody using the Wilcoxon rank sum test. The sensitivity and specificity for each marker were compared. RESULTS All 3 antibodies showed high sensitivity (100%) in identifying epithelial downgrowth. However, the specificity was greatest for MUC 16 (100%) compared with cytokeratin 19 (80%) and cytokeratin AE1/AE3 (0%). None of the endothelial cells in any case showed reactivity to anti-MUC16 compared with anti-cytokeratin AE1/AE3 (mean [SD], 0.0% [0.0%] vs 17.4% [10.4%]; P = .008). Cytokeratin 19 was positive in every case of epithelial downgrowth but showed focal staining of the endothelium (3.4% of cells) in 1 control. CONCLUSIONS Antibodies for MUC16, cytokeratin AE1/AE3, and cytokeratin 19 are equally sensitive for downgrowth. However, anti-MUC16 showed superior specificity compared with anti-cytokeratin 19 or anti-cytokeratin AE1/AE3 in this study.
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Affiliation(s)
- Vicky C Pai
- Department of Ophthalmology, Jules Stein Eye Institute, University of California at Los Angeles School of Medicine, Los Angeles, CA 90095-7000, USA
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Affiliation(s)
- Ben J Glasgow
- Department of Ophthalmology, Jules Stein Eye Institute, UCLA Medical Center, University of California-Los Angeles, 100 Stein Plaza, Los Angeles, CA 90095, USA.
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Ranchod TM, Quiram PA, Hathaway N, Ho LY, Glasgow BJ, Trese MT. Microcornea, posterior megalolenticonus, persistent fetal vasculature, and coloboma: a new syndrome. Ophthalmology 2010; 117:1843-7. [PMID: 20417569 DOI: 10.1016/j.ophtha.2009.12.045] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Revised: 12/29/2009] [Accepted: 12/30/2009] [Indexed: 10/19/2022] Open
Abstract
PURPOSE To report a newly identified syndrome of bilateral microcornea, posterior megalolenticonus, persistent fetal vasculature, and chorioretinal coloboma (MPPC). DESIGN Noncomparative case series. PARTICIPANTS Eight patients with MPPC syndrome. METHODS Clinical data collected retrospectively included visual acuity, findings on office examination as well as examination under anesthesia, and, in some cases, fluorescein angiography. Intraoperative findings and postoperative visual acuity and clinical findings were recorded when surgical intervention was performed. MAIN OUTCOME MEASURES Clinical description, intraoperative findings, and surgical outcomes. RESULTS All patients were found to have microcornea with corneal diameters of less than 8 mm. In all cases, the crystalline lens was found to be retrodisplaced with massive enlargement and a dramatic posterior lenticonus (posterior megalolenticonus), and the ciliary processes frequently were drawn to the lens capsule. A stalk of persistent fetal vascular tissue extended from the posterior pole of the lens to the optic disc. Posterior chorioretinal coloboma was present in all cases. Some cases also exhibited grossly dysplastic retina. Presentation frequently was asymmetric. Eight eyes of 6 patients underwent lensectomy, vitrectomy, membrane peeling, and fluid-Healon exchange (Healon OVD [sodium hyaluronate]; Advanced Medical Optics, Santa Ana, CA) with functional vision in at least 4 of the 5 patients with postsurgical follow-up. CONCLUSIONS Bilateral microcornea, posterior megalolenticonus, persistent fetal vasculature, and chorioretinal coloboma syndrome is a distinct syndrome previously unreported, to the authors' knowledge, and appropriate surgical intervention may result in significantly improved visual function.
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Gasymov OK, Abduragimov AR, Glasgow BJ. Excited protein states of human tear lipocalin for low- and high-affinity ligand binding revealed by functional AB loop motion. Biophys Chem 2010; 149:47-57. [PMID: 20439130 DOI: 10.1016/j.bpc.2010.03.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Revised: 03/22/2010] [Accepted: 03/28/2010] [Indexed: 10/19/2022]
Abstract
Human tear lipocalin (TL), a prominent member of lipocalin family, exhibits functional and structural promiscuity. The plasticity of loop regions modulates entry to the ligand pocket at the "open" end of the eight-stranded beta-barrel. Site-directed multi-distance measurements using fluorescence resonance energy transfer between functional loops register two excited protein states for low- and high-affinity ligand binding. At low pH, the longest loop AB adopts the conformation of the low-affinity excited protein state that matches the crystal structure of holo-TL at pH 8. A "crankshaft" like movement is detected for the loop AB in a low pH transition. At pH 7.3 the holo-protein assumes a high-affinity excited protein state, in which the loop AB is more compact (RMS=3.1A). In the apo-holo transition, the reporter Trp 28 moves about 4.5A that reflects a decrease in distance between Glu27 and Lys108. This interaction fixes the loop AB conformation for the high-affinity mode. No such movement is detected at low pH, where Glu27 is protonated. Data strongly indicate that the protonation state of Glu27 modulates the conformation of the loop AB for high- and low-affinity binding.
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Affiliation(s)
- Oktay K Gasymov
- Department of Pathology, University of California at Los Angeles, USA.
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Glasgow BJ, Gasymov OK, Abduragimov AR, Engle JJ, Casey RC. Tear lipocalin captures exogenous lipid from abnormal corneal surfaces. Invest Ophthalmol Vis Sci 2010; 51:1981-7. [PMID: 19959641 PMCID: PMC2868392 DOI: 10.1167/iovs.09-4622] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Revised: 10/25/2009] [Accepted: 11/06/2009] [Indexed: 01/02/2023] Open
Abstract
Purpose. The cornea is protected by apical hydrophilic transmembrane mucins and tears. In pathologic states the mucin barrier is disrupted, creating potential for meibomian lipids to adhere more strongly. Undisplaced lipids create an unwettable surface. The hypothesis that pathologic ocular surfaces alter lipid binding and the ability of tear proteins to remove lipids was tested. Methods. Corneas with pathologic surfaces were studied for lipid adhesion and removal by tears. Capture of fluorescence-labeled phospholipids by human tears was assessed by steady state fluorometry. Tear proteins were separated by gel filtration chromatography and analyzed for bound lipids. Results. Contact angle measurements revealed strong lipid adherence to corneas submerged in buffer. Lower contact angles are observed for lipids on completely de-epithelialized corneas compared with intact corneas (P = 0.04). Lipid removal from these surfaces is greater with whole tears than with tears depleted of tear lipocalin (P < 0.0005). Significantly fewer lipids are captured by tears from Bowman's layer than from epithelial-bearing surfaces (P < 0.025). The only tear component to bind the fluorescence-tagged lipid is tear lipocalin. The histology of a rare case of dry eye disease demonstrates the dominant features of contemporaneous bullous keratopathy. Lipid sequestration from this cornea by tear lipocalin was robust. Conclusions. Lipid is captured by tear lipocalin from corneas with bullous keratopathy and dry eye. Lipid removal is slightly abrogated by greater lipid adhesion to Bowman's layer. Reduced secretion of tear lipocalin documented in dry eye disease could hamper lipid removal and exacerbate ocular surface pathology.
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Affiliation(s)
- Ben J Glasgow
- Departments of Pathology, UCLA School of Medicine, Los Angeles, California, USA.
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Gasymov OK, Abduragimov AR, Glasgow BJ. pH-Dependent conformational changes in tear lipocalin by site-directed tryptophan fluorescence. Biochemistry 2010; 49:582-90. [PMID: 20025287 DOI: 10.1021/bi901435q] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Tear lipocalin (TL), a major protein of human tears, binds a broad array of endogenous ligands. pH-dependent ligand binding in TL may have functional implications in tears. Previously, conformational selections of the AB and GH loops have been implicated in ligand binding by site-directed tryptophan fluorescence (SDTF). In this study, SDTF was applied to the AB and GH loops to investigate pH-driven conformational changes relevant to ligand binding. Both loops demonstrate significant but distinct conformational rearrangements over a wide pH range. In the low-pH transition, from 7.3 to 3.0, residues of the GH loop exhibit decreased solvent accessibilities. In acrylamide quenching experiments, the average quenching rate constant (k(q), accessibility parameter) of the residues in the GH loop is decreased approximately 38%, from 2.1 x 10(9) to 1.3 x 10(9) M(-1) s(-1). However, despite the significant changes in accessibilities for some residues in the AB loop, the average accessibility per residue remained unchanged (average k(q) = 1.2 M(-1) s(-1)). Accordingly, the low-pH transition induces conformational changes that reshuffle the accessibility profiles of the residues in the AB loop. A significant difference in the titration curves between the holo and apo forms of the W28 mutant suggests that the protonation states of the residues around position 28 modulate conformational switches of the AB loop relevant to ligand binding.
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Affiliation(s)
- Oktay K Gasymov
- Department of Pathology, UCLA School of Medicine, Jules Stein Eye Institute, 100 Stein Plaza, Los Angeles, California 90095, USA
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Gasymov OK, Abduragimov AR, Glasgow BJ. Intracavitary ligand distribution in tear lipocalin by site-directed tryptophan fluorescence. Biochemistry 2009; 48:7219-28. [PMID: 19586017 DOI: 10.1021/bi9005557] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Site-directed tryptophan fluorescence has been successfully used to determine the solution structure of tear lipocalin. Here, the technique is extended to measure the binding energy landscape. Single Trp mutants of tear lipocalin are bound to the native ligand and an analogue tagged with a quencher group to both populate and discriminate the excited protein states. Steady-state and time-resolved fluorescence quenching data reveal the intracavitary state of the ligand. The static components of fluorescence quenching identify the residues where nonfluorescence complexes form. An asymmetric distribution of the ligand within the cavity reflects the complex energy landscape of the excited protein states. These findings suggest that the excited protein states are not unique but consist of many substates. The roughness of the binding energy landscape is about 2.5kBT. The excited protein states originate primarily from conformational selections of loops AB and GH, a portal region. In contrast to static quenching, the dynamic components of fluorescence quenching by the ligand are relevant to both local side chain and ligand dynamics. Apparent bimolecular rate constants for collisional quenching of Trp by the nitroxide moiety are approximately 1 / 5 x 10(12) M(-1) s(-1). Estimations made for effective ligand concentrations establish actual rate constants on the order of 12 x 10(9) M(-1) s(-1). Prior to exit from the cavity of the protein, ligands explore binding sites in nanoseconds. Although microsecond fluctuations are rate-limiting processes in ligand binding for many proteins, accompanying nanosecond motion may be necessary for propagation of ligand binding.
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Affiliation(s)
- Oktay K Gasymov
- Department of Pathology, UCLA School of Medicine, Jules Stein Eye Institute, 100 Stein Plaza, Los Angeles, California 90095, USA
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Abstract
PURPOSE Expression of cellular adhesion molecules is altered in bullous keratopathy. The hypothesis that epithelial alterations in bullous keratopathy compromise the surface of the cornea and its glycocalyx was tested. METHODS Studies were performed on eight cases each of pseudophakic bullous keratopathy and healthy corneas. The number of epithelial cell layers was determined with a stereological method of point counting. The minimum distance between points was established by estimates of cell size with variable pressure scanning electron microscopy performed in backscatter mode. The mean number of cell layers with mucin expression was identified by immunohistochemistry with mouse monoclonal antibodies for MUC1 and MUC16. Data were analyzed by Student's t-test if values showed a normal distribution or, alternatively, by the Wilcoxon rank-sum test. RESULTS Mean numbers of wing cell and superficial cell layers were lower in bullous keratopathy specimens (1.6 vs. 2.0; P < 0.0001) than in controls (1.1 vs. 1.8; P < 0.000001). The number of exfoliated cell layers evident in sections was increased in the bullous keratopathy specimens compared with controls (0.36 vs. 0.03; P < 0.0001). The number of cell layers decorated with antibodies to MUC16 was lower in bullous keratopathy specimens than in controls (0.5 vs. 1.2; P < 0.025). The reduction of layers expressing MUC1 in bullous keratopathy was not statistically significant. CONCLUSIONS Pseudophakic bullous keratopathy manifests an abnormal corneal ocular surface in which superficial cell layers are exfoliated, leaving breaches in the protective MUC16 glycocalyx. The results provide a morphologic correlate for the surface epithelial abnormalities noted clinically in these patients.
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Affiliation(s)
- Ben J Glasgow
- Departments of Pathology, Jules Stein Eye Institute, University of California at Los Angeles School of Medicine, Los Angeles, California, USA.
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Yu L, Aldave AJ, Glasgow BJ. Epstein-Barr virus-associated smooth muscle tumor of the iris in a patient with transplant: a case report and review of the literature. Arch Pathol Lab Med 2009; 133:1238-41. [PMID: 19653717 DOI: 10.5858/133.8.1238] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/20/2009] [Indexed: 11/06/2022]
Abstract
Epstein-Barr virus infection has been linked to the development of smooth muscle tumors in immunocompromised patients with organ transplants and acquired immunodeficiency syndrome. A 52-year-old female recipient of a renal transplant presented with enlarging masses of the left iris. Incisional biopsy of the mass revealed a smooth muscle tumor of the iris. Epstein-Barr virus infection was confirmed by in situ hybridization for Epstein-Barr virus-encoded, small RNA in tumor cells. Eight months after total iridectomy the patient was free of disease. Although the prognosis and classification of Epstein-Barr virus-associated smooth muscle tumors are controversial, mortalities caused by these tumors are rare.
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Affiliation(s)
- Le Yu
- Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, 10833 Le Conte Ave, Los Angeles, CA 90095, USA
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