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Ziai Y, Rinoldi C, Petronella F, Zakrzewska A, De Sio L, Pierini F. Lysozyme-sensitive plasmonic hydrogel nanocomposite for colorimetric dry-eye inflammation biosensing. NANOSCALE 2024; 16:13492-13502. [PMID: 38940682 DOI: 10.1039/d4nr01701c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/29/2024]
Abstract
Detection of lysozyme levels in ocular fluids is considered crucial for diagnosing and monitoring various health and eye conditions, including dry-eye syndrome. Hydrogel-based nanocomposites have been demonstrated to be one of the most promising platforms for fast and accurate sensing of different biomolecules. In this work, hydrogel, electrospun nanofibers, and plasmonic nanoparticles are combined to fabricate a sensitive and easy-to-use biosensor for lysozyme. Poly(L-lactide-co-caprolactone) (PLCL) nanofibers were covered with silver nanoplates (AgNPls), providing a stable plasmonic platform, where a poly(N-isopropylacrylamide)-based (PNIPAAm) hydrogel layer allows mobility and good integration of the biomolecules. By integrating these components, the platform can also exhibit a colorimetric response to the concentration of lysozyme, allowing for easy and non-invasive monitoring. Quantitative biosensing operates on the principle of localized surface plasmon resonance (LSPR) induced by plasmonic nanoparticles. Chemical, structural, thermal, and optical characterizations were performed on each platform layer, and the platform's ability to detect lysozyme at concentrations relevant to those found in tears of patients with dry-eye syndrome and other related diseases was investigated by colorimetry and UV-Vis spectroscopy. This biosensor's sensitivity and rapid response time, alongside the easy detection by the naked eye, make it a promising tool for early diagnosis and treatment monitoring of eye diseases.
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Affiliation(s)
- Yasamin Ziai
- Department of Biosystems and Soft Matter, Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Chiara Rinoldi
- Department of Biosystems and Soft Matter, Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Francesca Petronella
- National Research Council of Italy, Institute of Crystallography CNR-IC, Area della Ricerca Roma 1 Strada Provinciale 35d, n. 9, 00010, Montelibretti (RM), Italy.
| | - Anna Zakrzewska
- Department of Biosystems and Soft Matter, Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Luciano De Sio
- Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Corso della Repubblica 79, 04100 Latina, Italy
| | - Filippo Pierini
- Department of Biosystems and Soft Matter, Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw 02-106, Poland
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2
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Muñoz G, Millicovsky M, Cerrudo J, Peñalva A, Machtey M, Reta J, Torres R, Campana D, Zalazar M. Exploring tear viscosity with quartz crystal microbalance technology. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:075107. [PMID: 39023347 DOI: 10.1063/5.0207182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 07/03/2024] [Indexed: 07/20/2024]
Abstract
Tear viscosity is a critical property affecting tear distribution and ocular surface stability. While not widely established as a primary diagnostic marker, deviations from normal viscosity can impact ocular health, potentially contributing to conditions such as dry eye syndrome. Despite their importance, traditional viscometers require sample volumes that are not feasible to use with tear volume. This research introduces a novel Quartz Crystal Microbalance (QCM)-based method for tear viscosity measurement, offering a viscometer prototype that operates with minimal sample volumes. Human tear samples, solutions used in artificial eye drops, and various commercial eye drop brands were evaluated. Results show that the QCM method aligns with established viscosity ranges. The average viscosity of healthy human tears was found to be 1.73 ± 0.61 cP, aligning with the typical range of 1-10 cP. Variability in the viscosities of eye drop can be attributed to differences in their chemical compositions. The QCM method offers benefits such as reduced sample consumption and rapid results, enhancing understanding of tear dynamics for ocular health. Further research with larger sample sizes is needed to establish normative viscosity values in healthy individuals and those with dry eye syndrome, which is crucial for validating the device's clinical efficacy.
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Affiliation(s)
- G Muñoz
- Facultad de Ingeniería, Universidad Nacional de Entre Ríos, Ruta Prov. 11, Km 10, Oro Verde 3100, Entre Ríos, Argentina
| | - M Millicovsky
- Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática (CONICET-UNER), Ruta Prov. 11, Km 10, Oro Verde 3100, Entre Ríos, Argentina
| | - J Cerrudo
- Facultad de Ingeniería, Universidad Nacional de Entre Ríos, Ruta Prov. 11, Km 10, Oro Verde 3100, Entre Ríos, Argentina
| | - A Peñalva
- Facultad de Ingeniería, Universidad Nacional de Entre Ríos, Ruta Prov. 11, Km 10, Oro Verde 3100, Entre Ríos, Argentina
| | - M Machtey
- Facultad de Ingeniería, Universidad Nacional de Entre Ríos, Ruta Prov. 11, Km 10, Oro Verde 3100, Entre Ríos, Argentina
| | - J Reta
- Facultad de Ingeniería, Universidad Nacional de Entre Ríos, Ruta Prov. 11, Km 10, Oro Verde 3100, Entre Ríos, Argentina
| | - R Torres
- ROMAT Creator Center, Colonia Avellaneda, Entre Ríos, Argentina and Investigador Independiente, Colaborador de la Facultad de Ingeniería, Universidad Nacional de Entre Ríos, Ruta Prov. 11, Km 10, Oro Verde 3100, Entre Ríos, Argentina
| | - D Campana
- Facultad de Ingeniería, Universidad Nacional de Entre Ríos, Ruta Prov. 11, Km 10, Oro Verde 3100, Entre Ríos, Argentina
- Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática (CONICET-UNER), Ruta Prov. 11, Km 10, Oro Verde 3100, Entre Ríos, Argentina
| | - M Zalazar
- Facultad de Ingeniería, Universidad Nacional de Entre Ríos, Ruta Prov. 11, Km 10, Oro Verde 3100, Entre Ríos, Argentina
- Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática (CONICET-UNER), Ruta Prov. 11, Km 10, Oro Verde 3100, Entre Ríos, Argentina
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Sarmento C, Duarte ARC, Rita Jesus A. Can (Natural) deep eutectic systems increase the efficacy of ocular therapeutics? Eur J Pharm Biopharm 2024; 198:114276. [PMID: 38582179 DOI: 10.1016/j.ejpb.2024.114276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 03/12/2024] [Accepted: 04/03/2024] [Indexed: 04/08/2024]
Abstract
The eye is one of the most complex organs in the human body, with a unique anatomy and physiology, being divided into anterior and posterior segments. Ocular diseases can occur in both segments, but different diseases affect different segments. Glaucoma and cataracts affect the anterior segment, while macular degeneration and diabetic retinopathy occur in the posterior segment. The easiest approach to treat ocular diseases, especially in the anterior segment, is through the administration of topical eye drops, but this route presents many constraints, namely precorneal dynamic and static ocular barriers. On the other hand, the delivery of drugs to the posterior segment of the eye is far more challenging and is mainly performed by the intravitreal route. However, it can lead to severe complications such as retinal detachment, endophthalmitis, increased intraocular pressure and haemorrhage. The design of new drug delivery systems for the anterior segment is very challenging, but targeting the posterior one is even more difficult and little progress has been made. In this review we will discuss various strategies including the incorporation of additives in the formulations, such as viscosity, permeability, and solubility enhancers, namely based on Deep eutectic systems (DES). Natural deep eutectic systems (NADES) have emerged to solve several problems encountered in pharmaceutical industry, regarding the pharmacokinetic and pharmacodynamic properties of drugs. NADES can contribute to the design of advanced technologies for ocular therapeutics, including hydrogels and nanomaterials. Here in, we revise some applications of (NA)DES in the development of new drug delivery systems that can be translated into the ophthalmology field.
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Affiliation(s)
- Célia Sarmento
- LAQV-REQUIMTE, Chemistry Department, NOVA - School of Science and Technology, 2829-516 Caparica, Portugal
| | - Ana Rita C Duarte
- LAQV-REQUIMTE, Chemistry Department, NOVA - School of Science and Technology, 2829-516 Caparica, Portugal
| | - Ana Rita Jesus
- LAQV-REQUIMTE, Chemistry Department, NOVA - School of Science and Technology, 2829-516 Caparica, Portugal.
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4
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Vasquez PA, Walker B, Bloom K, Kolbin D, Caughman N, Freeman R, Lysy M, Hult C, Newhall KA, Papanikolas M, Edelmaier C, Forest MG. The power of weak, transient interactions across biology: A paradigm of emergent behavior. PHYSICA D. NONLINEAR PHENOMENA 2023; 454:133866. [PMID: 38274029 PMCID: PMC10806540 DOI: 10.1016/j.physd.2023.133866] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2024]
Abstract
A growing list of diverse biological systems and their equally diverse functionalities provides realizations of a paradigm of emergent behavior. In each of these biological systems, pervasive ensembles of weak, short-lived, spatially local interactions act autonomously to convey functionalities at larger spatial and temporal scales. In this article, a range of diverse systems and functionalities are presented in a cursory manner with literature citations for further details. Then two systems and their properties are discussed in more detail: yeast chromosome biology and human respiratory mucus.
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Affiliation(s)
- Paula A. Vasquez
- Department of Mathematics, University of South Carolina, United States of America
| | - Ben Walker
- Department of Mathematics, University of California at Irvine, United States of America
| | - Kerry Bloom
- Department of Biology, University of North Carolina at Chapel Hill, United States of America
| | - Daniel Kolbin
- Department of Biology, University of North Carolina at Chapel Hill, United States of America
| | - Neall Caughman
- Department of Mathematics, University of North Carolina at Chapel Hill, United States of America
| | - Ronit Freeman
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, United States of America
| | - Martin Lysy
- Department of Statistics and Actuarial Science, University of Waterloo, Canada
| | - Caitlin Hult
- Department of Mathematics, Gettysburg College, United States of America
| | - Katherine A. Newhall
- Department of Mathematics, University of North Carolina at Chapel Hill, United States of America
| | - Micah Papanikolas
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, United States of America
| | - Christopher Edelmaier
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, United States of America
- Center for Computational Biology, Flatiron Institute, United States of America
| | - M. Gregory Forest
- Department of Mathematics, University of North Carolina at Chapel Hill, United States of America
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, United States of America
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Dong S, Zhang N, Yi M, Zhang J, Di D, Deng J, Li L, Hu B. Slug-Flow Microextraction Mass Spectrometry for Enhanced Detection of Analytes in Human Tear Fluids using Noninvasive Microsampling and Nanoelectrospray Ionization via a Capillary. Anal Chem 2023; 95:16054-16058. [PMID: 37852267 DOI: 10.1021/acs.analchem.3c03683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
In vivo noninvasive sampling and sensitive analysis of human tear fluids at the microliter level is an important but challenging task in investigating eye health. In this work, capillary microsampling coupled with slug-flow microextraction mass spectrometry (SFME-MS) was developed for enhanced detection of analytes in human tear fluids. As low as 1.0 μL of human tear fluid could be directly sampled using a capillary, and extraction/spray solvent was then loaded into the capillary to perform slug-flow microextraction and direct nanoelectrospray ionization (nESI) of analytes. All analytical procedures, including tear microsampling, microextraction, and ionization of analytes, were performed using a capillary. Enhanced detection of therapeutic drugs and disease biomarkers in human tear fluids was successfully demonstrated. Acceptable analytical performances including sensitivity, reproducibility, and quantitation were obtained. It is found that the use of SFME could improve the nESI-MS detection of trace analytes over 100-fold that depends on the chemical properties of analytes. Overall, this study showed that SFME-nESI-MS is a highly effective method for enhanced detection of trace analytes in tear fluids and is expected to be a potentially powerful tool in significant biological and clinical applications.
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Affiliation(s)
- Songbin Dong
- Institute of Mass Spectrometry and Atmospheric Environment, Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Guangdong Provincial Key Laboratory of Speed Capability Research, Jinan University, Guangzhou 510632, China
| | - Ning Zhang
- Ophthalmology Department, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710064, China
| | - Man Yi
- Institute of Mass Spectrometry and Atmospheric Environment, Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Guangdong Provincial Key Laboratory of Speed Capability Research, Jinan University, Guangzhou 510632, China
| | - Jianfeng Zhang
- Institute of Mass Spectrometry and Atmospheric Environment, Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Guangdong Provincial Key Laboratory of Speed Capability Research, Jinan University, Guangzhou 510632, China
| | - Dandan Di
- Institute of Mass Spectrometry and Atmospheric Environment, Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Guangdong Provincial Key Laboratory of Speed Capability Research, Jinan University, Guangzhou 510632, China
| | - Jiewei Deng
- School of Biomedical and Pharmaceutical Sciences, Smart Medical Innovation Technology Center, Guangdong University of Technology, Guangzhou 510006, China
| | - Lei Li
- Institute of Mass Spectrometry and Atmospheric Environment, Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Guangdong Provincial Key Laboratory of Speed Capability Research, Jinan University, Guangzhou 510632, China
| | - Bin Hu
- Institute of Mass Spectrometry and Atmospheric Environment, Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Guangdong Provincial Key Laboratory of Speed Capability Research, Jinan University, Guangzhou 510632, China
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6
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Lai HY, Chen A, Fang PC, Yu HJ, Kuo MT. Comparing Tear Film Viscosity between Sjögren and Non-Sjögren Dry Eye Disease. Life (Basel) 2023; 13:1484. [PMID: 37511859 PMCID: PMC10381532 DOI: 10.3390/life13071484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 06/27/2023] [Accepted: 06/28/2023] [Indexed: 07/30/2023] Open
Abstract
This study aimed to compare tear film viscosity (TFV) in Sjögren and non-Sjögren dry eye diseases (DEDs). This was a cross-sectional observational study. A total of 68 DED patients were enrolled, including 32 patients with Sjögren syndrome (SS) and 36 without SS. TFV was assessed by a tear film analyzer and determined by the momentary moving speed (MMS; MMS (t) = α × t-β, t = time (s)) with its power-law fitting-derived parameters (α and β). Among the four indices of TFV (MMS (0.1 s), MMS (2.0 s), α, and β), the SS-DED patients had significantly lower MMS (0.1 s) (p = 2.01 × 10-5), α (p = 0.0375), and β (p = 0.0076). The SS-DED group also had significantly higher OSDI, lower central and nasal tear meniscus height (TMH), and higher OSS. MMS (0.1 s) was significantly correlated with nasal TMH and OSS (ρ = 0.2520, p = 0.0381 in nasal TMH; ρ = -0.3487, p = 0.0036 in OSS). Index β was not correlated with any non-TFV tests. In conclusion, MMS (0.1 s), α, and β are promising TFV indices in distinguishing SS-DED from non-SS-DED patients early. Among these TFV indices, lower MMS is the best alternative clue for detecting SS-DED.
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Affiliation(s)
- Hung-Yin Lai
- Department of Ophthalmology, China Medical University Hospital, China Medical University, Taichung City 40402, Taiwan
| | - Alexander Chen
- Department of Ophthalmology, Antai Medical Care Cooperation Antai Tian-Sheng Memorial Hospital, Pingtung City 92842, Taiwan
| | - Po-Chiung Fang
- Department of Ophthalmology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung City 83301, Taiwan
- School of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
| | - Hun-Ju Yu
- Department of Ophthalmology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung City 83301, Taiwan
| | - Ming-Tse Kuo
- Department of Ophthalmology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung City 83301, Taiwan
- School of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
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7
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Sarmento C, Monteiro H, Paiva A, Duarte ARC, Jesus AR. Using Natural Deep Eutectic Systems as Alternative Media for Ocular Applications. Pharmaceutics 2023; 15:pharmaceutics15051553. [PMID: 37242795 DOI: 10.3390/pharmaceutics15051553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/17/2023] [Accepted: 05/19/2023] [Indexed: 05/28/2023] Open
Abstract
The major goal of this work was to study the potential of natural deep eutectic systems (NADES) as new media for ocular formulations. In formulating eye drops, it is important to increase the retention time of the drug on the surface of eye; hence, due to their high viscosity, NADES may be interesting candidates for formulation. Different systems composed of combinations of sugars, polyols, amino acids, and choline derivatives were prepared and then characterized in terms of rheological and physicochemical properties. Our results showed that 5-10% (w/v) aqueous solutions of NADES have a good profile in terms of viscosity (0.8 to 1.2 mPa.s), osmolarity (412 to 1883 mOsmol), and pH (7.4) for their incorporation of ocular drops. Additionally, contact angle and refractive index were determined. Acetazolamide (ACZ), a highly insoluble drug used to treat glaucoma, was used as proof-of-concept. Herein, we show that NADES can increase the solubility of ACZ in aqueous solutions by at least up to 3 times, making it useful for the formulation of ACZ into ocular drops and thereby enabling more efficient treatment. The cytotoxicity assays demonstrated that NADES are biocompatible up to 5% (w/v) in aqueous media, promoting cell viability (above 80%) when compared to the control after 24 h incubation in ARPE-19 cells. Furthermore, when ACZ is dissolved in aqueous solutions of NADES, the cytotoxicity is not affected in this range of concentrations. Although further studies are necessary to design an optimal formulation incorporating NADES, this study shows that these eutectics can be powerful tools in the formulation of ocular drugs.
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Affiliation(s)
- Célia Sarmento
- LAQV-REQUIMTE, Chemistry Department, NOVA-School of Science and Technology, 2829-516 Caparica, Portugal
| | - Hugo Monteiro
- LAQV-REQUIMTE, Chemistry Department, NOVA-School of Science and Technology, 2829-516 Caparica, Portugal
| | - Alexandre Paiva
- LAQV-REQUIMTE, Chemistry Department, NOVA-School of Science and Technology, 2829-516 Caparica, Portugal
| | - Ana Rita C Duarte
- LAQV-REQUIMTE, Chemistry Department, NOVA-School of Science and Technology, 2829-516 Caparica, Portugal
| | - Ana Rita Jesus
- LAQV-REQUIMTE, Chemistry Department, NOVA-School of Science and Technology, 2829-516 Caparica, Portugal
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8
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Biochemistry of human tear film: A review. Exp Eye Res 2022; 220:109101. [DOI: 10.1016/j.exer.2022.109101] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 04/18/2022] [Accepted: 04/26/2022] [Indexed: 12/13/2022]
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Recchioni A, Mocciardini E, Ponzini E, Tavazzi S. Viscoelastic properties of the human tear film. Exp Eye Res 2022; 219:109083. [PMID: 35460666 DOI: 10.1016/j.exer.2022.109083] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/25/2022] [Accepted: 04/18/2022] [Indexed: 12/21/2022]
Abstract
When considering eye blinking from a tribological perspective, tear viscosity is expected to play a fundamental role. The application of rheological techniques to describe the tear film dates back to the late 1980s, but there has been a continuous need of reappraisal due to new findings in tear film biochemistry and to the development of new methods of physico-chemical characterization. This review provides an overview on tear rheological behavior by analyzing the peer-reviewed literature on this topic. Specifically, examples of in-vitro and in-vivo viscosity measurements are detailed, highlighting experimental criticalities and the need of a standard convention for rheological techniques to compare data across different studies, of analyses on tears of single individuals even within the limits of the low volume available, and of a further development of in-vivo techniques. Then, the controversial role of specific tear components on viscosity is discussed, together with the alterations associated to dry eye disease and contact lens wear. Finally, an updated focus is reported on the viscosity of artificial tears formulations.
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Affiliation(s)
- Alberto Recchioni
- Academic Unit of Ophthalmology, Institute of Inflammation and Ageing, University of Birmingham, UK; Optometry & Vision Sciences Group, School of Life & Health Sciences, Aston University, Birmingham, UK; Birmingham and Midland Eye Centre, Birmingham, UK
| | - Emanuele Mocciardini
- University of Milano Bicocca, Corso di laurea in Ottica e Optometria, via R. Cozzi 55, I-20125, Milan, Italy
| | - Erika Ponzini
- University of Milano Bicocca, Materials Science Department, via R. Cozzi 55, I-20125, Milan, Italy; University of Milano Bicocca, COMiB research center, via R. Cozzi 55, I-20125, Milan, Italy.
| | - Silvia Tavazzi
- University of Milano Bicocca, Materials Science Department, via R. Cozzi 55, I-20125, Milan, Italy; University of Milano Bicocca, COMiB research center, via R. Cozzi 55, I-20125, Milan, Italy
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Wu W, Huang S, Xie X, Chen C, Yan Z, Lv X, Fan Y, Chen C, Yue F, Yang B. Raman spectroscopy may allow rapid noninvasive screening of keratitis and conjunctivitis. Photodiagnosis Photodyn Ther 2021; 37:102689. [PMID: 34933166 DOI: 10.1016/j.pdpdt.2021.102689] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 10/30/2021] [Accepted: 12/10/2021] [Indexed: 10/19/2022]
Abstract
Keratitis and conjunctivitis are the most common ocular diseases, their symptoms are similar and easy to confuse, however infectious conjunctivitis is highly contagious. If misdiagnosed, it may worsen the disease and pose a threat to public health.This is a preclinical study to propose a method for rapid and accurate screening of keratitis and conjunctivitis by combining tear Raman spectroscopy with deep learning models that may be applied to clinical applications in the future.The tears of 16 cases of keratitis patients, 13 cases of conjunctivitis patients and 46 cases of healthy subjects were collected, and their Raman spectra were compared and analyzed. By adding different decibels of Gaussian white noise to expand the data, the performance of the tear Raman spectra with a large sample size in the deep learning model was discussed. Principal component analysis (PCA), partial least squares (PLS) and maximum correlation minimum redundancy (mRMR) were used for feature extraction. The processed data were imported into convolutional neural network (CNN) and recurrent neural network (RNN) depth models for classification. After the data were enhanced and processed by PLS, the highest classification accuracy of healthy subjects and keratitis patients, healthy subjects and conjunctivitis patients, and keratitis and conjunctivitis patients reached 94.8%, 95.4%, and 92.7%, respectively. The results of this study show that the use of large sample tear Raman spectra data combined with PLS feature extraction and depth learning algorithms may have great potential in clinical screening of keratitis and conjunctivitis.
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Affiliation(s)
- Wei Wu
- College of Software, Xinjiang University, Urumqi 830046, China
| | - Shengsong Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, 510060 China
| | - Xiaodong Xie
- People's Hospital of Xinjiang Uygur Autonomous Region, 91 Tianchi Road, Ophthalmology, Urumqi 830001, China.
| | - Cheng Chen
- College of Information Science and Engineering, Xinjiang University, Urumqi 830046, China.
| | - Ziwei Yan
- College of Information Science and Engineering, Xinjiang University, Urumqi 830046, China; Key Laboratory of signal detection and processing, Xinjiang University, Urumqi 830046, China
| | - Xiaoyi Lv
- College of Software, Xinjiang University, Urumqi 830046, China; Key Laboratory of signal detection and processing, Xinjiang University, Urumqi 830046, China
| | - Yangyang Fan
- College of Software, Xinjiang University, Urumqi 830046, China
| | - Chen Chen
- College of Information Science and Engineering, Xinjiang University, Urumqi 830046, China; Key Laboratory of signal detection and processing, Xinjiang University, Urumqi 830046, China
| | - Feilong Yue
- College of Software, Xinjiang University, Urumqi 830046, China
| | - Bo Yang
- College of Information Science and Engineering, Xinjiang University, Urumqi 830046, China
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11
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Sahu DK, Pradhan D, Biswasroy P, Kar B, Ghosh G, Rath G. Recent trends in nanocarrier based approach in the management of dry eye disease. J Drug Deliv Sci Technol 2021. [DOI: 10.1016/j.jddst.2021.102868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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12
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Glasgow BJ. Tear Lipocalin and Lipocalin-Interacting Membrane Receptor. Front Physiol 2021; 12:684211. [PMID: 34489718 PMCID: PMC8417070 DOI: 10.3389/fphys.2021.684211] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 07/13/2021] [Indexed: 11/24/2022] Open
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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13
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Hutchinson RB, Chen X, Zhou N, Cavagnero S. Fluorescence Anisotropy Decays and Microscale-Volume Viscometry Reveal the Compaction of Ribosome-Bound Nascent Proteins. J Phys Chem B 2021; 125:6543-6558. [PMID: 34110829 PMCID: PMC8741338 DOI: 10.1021/acs.jpcb.1c04473] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
This work introduces a technology that combines fluorescence anisotropy decay with microscale-volume viscometry to investigate the compaction and dynamics of ribosome-bound nascent proteins. Protein folding in the cell, especially when nascent chains emerge from the ribosomal tunnel, is poorly understood. Previous investigations based on fluorescence anisotropy decay determined that a portion of the ribosome-bound nascent protein apomyoglobin (apoMb) forms a compact structure. This work, however, could not assess the size of the compact region. The combination of fluorescence anisotropy with microscale-volume viscometry, presented here, enables identifying the size of compact nascent-chain subdomains using a single fluorophore label. Our results demonstrate that the compact region of nascent apoMb contains 57-83 amino acids and lacks residues corresponding to the two native C-terminal helices. These amino acids are necessary for fully burying the nonpolar residues in the native structure, yet they are not available for folding before ribosome release. Therefore, apoMb requires a significant degree of post-translational folding for the generation of its native structure. In summary, the combination of fluorescence anisotropy decay and microscale-volume viscometry is a powerful approach to determine the size of independently tumbling compact regions of biomolecules. This technology is of general applicability to compact macromolecules linked to larger frameworks.
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Affiliation(s)
| | - Xi Chen
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706
| | - Ningkun Zhou
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706
| | - Silvia Cavagnero
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706
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14
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López-Cano JJ, González-Cela-Casamayor MA, Andrés-Guerrero V, Herrero-Vanrell R, Molina-Martínez IT. Liposomes as vehicles for topical ophthalmic drug delivery and ocular surface protection. Expert Opin Drug Deliv 2021; 18:819-847. [PMID: 33412914 DOI: 10.1080/17425247.2021.1872542] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Introduction: The development of ophthalmic formulations able to deliver hydrophilic and hydrophobic drugs to the inner structures of the eye and restore the preocular tear film has been a leading topic of discussion over the last few years. In this sense, liposomes represent a suitable strategy to achieve these objectives in ocular drug delivery.Areas covered: Knowledge of the different physiological and anatomical eye structures, and specially the ocular surface are critical to better understanding and comprehending the characteristics required for the development of topical ophthalmic liposomal formulations. In this review, several features of liposomes are discussed such as the main materials used for their fabrication, basic structure and preparation methods, from already established to novel techniques, allowing the control and design of special characteristics. Besides, physicochemical properties, purification processes and strategies to overcome delivery or encapsulation challenges are also presented. Expert opinion: Regarding ocular drug delivery of liposomes, there are some features that can be redesigned. Specific biocompatible and biodegradable materials presenting therapeutic properties, such as lipidic compounds or polymers significantly change the way of tackling ophthalmic diseases. Besides, liposomes entail an effective, safe and versatile strategy for the treatment of diseases in the clinical practice.
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Affiliation(s)
- José Javier López-Cano
- Department of Pharmaceutics and Food Technology, Complutense University, Madrid, Spain.,Ocular Pathology National Net (OFTARED) of the Institute of Health Carlos III, Health Research Institute of the San Carlos Clinical Hospital (Idissc), Madrid Spain
| | - Miriam Ana González-Cela-Casamayor
- Department of Pharmaceutics and Food Technology, Complutense University, Madrid, Spain.,Ocular Pathology National Net (OFTARED) of the Institute of Health Carlos III, Health Research Institute of the San Carlos Clinical Hospital (Idissc), Madrid Spain
| | - Vanessa Andrés-Guerrero
- Department of Pharmaceutics and Food Technology, Complutense University, Madrid, Spain.,Ocular Pathology National Net (OFTARED) of the Institute of Health Carlos III, Health Research Institute of the San Carlos Clinical Hospital (Idissc), Madrid Spain
| | - Rocío Herrero-Vanrell
- Department of Pharmaceutics and Food Technology, Complutense University, Madrid, Spain.,Ocular Pathology National Net (OFTARED) of the Institute of Health Carlos III, Health Research Institute of the San Carlos Clinical Hospital (Idissc), Madrid Spain
| | - Irene Teresa Molina-Martínez
- Department of Pharmaceutics and Food Technology, Complutense University, Madrid, Spain.,Ocular Pathology National Net (OFTARED) of the Institute of Health Carlos III, Health Research Institute of the San Carlos Clinical Hospital (Idissc), Madrid Spain
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15
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Orlowska MK, Guan B, Sedev R, Morikawa Y, Suu K, Priest C. Evaporation-Driven Flow in Micropillar Arrays: Transport Dynamics and Chemical Analysis under Varied Sample and Ambient Conditions. Anal Chem 2020; 92:16043-16050. [PMID: 33269908 DOI: 10.1021/acs.analchem.0c03667] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Microfluidic flow in lab-on-a-chip devices is typically very sensitive to the variable physical properties of complex samples, e.g., biological fluids. Here, evaporation-driven fluid transport (transpiration) is achieved in a configuration that is insensitive to interfacial tension, salinity, and viscosity over a wide range. Micropillar arrays ("pillar cuvettes") were preloaded by wicking a known volatile fluid (water) and then adding a microliter sample of salt, surfactant, sugar, or saliva solution to the loading zone. As the preloaded fluid evaporates, the sample is reliably drawn from a reservoir through the pillar array at a rate defined by the evaporation of the preloaded fluid (typically nL/s). Including a reagent in the preloaded fluid allows photometric reactions to take place at the boundary between the two fluids. In this configuration, a photometric signal enhancement is observed and chemical analysis is independent of both humidity and temperature. The ability to reliably transport and sense an analyte in microliter volumes without concern over salt, surfactant, viscosity (in part), humidity, and temperature is a remarkable advantage for analytical purposes.
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Affiliation(s)
- Marta K Orlowska
- Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Bin Guan
- Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Rossen Sedev
- Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
| | | | - Koukou Suu
- ULVAC Inc., 2500 Chigasaki, Hagisono, Kanagawa 253-8543, Japan
| | - Craig Priest
- Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia.,UniSA STEM, University of South Australia, Mawson Lakes, SA 5095, Australia
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16
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Georgiev GA, Gh MS, Romano J, Dias Teixeira KL, Struble C, Ryan DS, Sia RK, Kitt JP, Harris JM, Hsu KL, Libby A, Odrich MG, Suárez T, McKown RL, Laurie GW. Lacritin proteoforms prevent tear film collapse and maintain epithelial homeostasis. J Biol Chem 2020; 296:100070. [PMID: 33187980 PMCID: PMC7948570 DOI: 10.1074/jbc.ra120.015833] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 11/10/2020] [Accepted: 11/13/2020] [Indexed: 12/14/2022] Open
Abstract
Lipids in complex, protein-enriched films at air/liquid interfaces reduce surface tension. In the absence of this benefit, the light refracting and immunoprotective tear film on eyes would collapse. Premature collapse, coupled with chronic inflammation compromising visual acuity, is a hallmark of dry eye disease affecting 7 to 10% of individuals worldwide. Although collapse seems independent of mutation (unlike newborn lung alveoli), selective proteome and possible lipidome changes have been noted. These include elevated tissue transglutaminase and consequent inactivation through C-terminal cross-linking of the tear mitogen lacritin, leading to significant loss of lacritin monomer. Lacritin monomer restores homeostasis via autophagy and mitochondrial fusion and promotes basal tearing. Here, we discover that lacritin monomer C-terminal processing, inclusive of cysteine, serine, and metalloproteinase activity, generates cationic amphipathic α-helical proteoforms. Such proteoforms (using synthetic peptide surrogates) act like alveolar surfactant proteins to rapidly bind and stabilize the tear lipid layer. Immunodepletion of C- but not N-terminal proteoforms nor intact lacritin, from normal human tears promotes loss of stability akin to human dry eye tears. Stability of these and dry eye tears is rescuable with C- but not N-terminal proteoforms. Repeated topical application in rabbits reveals a proteoform turnover time of 7 to 33 h with gradual loss from human tear lipid that retains bioactivity without further processing. Thus, the processed C-terminus of lacritin that is deficient or absent in dry eye tears appears to play a key role in preventing tear film collapse and as a natural slow release mechanism that restores epithelial homeostasis.
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Affiliation(s)
- Georgi A Georgiev
- Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | | | - Jeff Romano
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia, USA
| | | | - Craig Struble
- Drug Metabolism, Covance Laboratories Inc, Madison, Wisconsin, USA
| | - Denise S Ryan
- Warfighter Refractive Eye Surgery Program and Research Center at Fort Belvoir, Fort Belvoir, Virginia, USA
| | - Rose K Sia
- Warfighter Refractive Eye Surgery Program and Research Center at Fort Belvoir, Fort Belvoir, Virginia, USA
| | - Jay P Kitt
- Department of Chemistry, University of Utah, Salt Lake City, Utah, USA
| | - Joel M Harris
- Department of Chemistry, University of Utah, Salt Lake City, Utah, USA
| | - Ku-Lung Hsu
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Adam Libby
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Marc G Odrich
- Department of Ophthalmology, University of Virginia, Charlottesville, Virginia, USA
| | - Tatiana Suárez
- Department of Research, Development and Innovation, FAES FARMA, Bizkaia, Spain
| | - Robert L McKown
- Department of Integrated Science and Technology, James Madison University, Harrisonburg, Virginia, USA
| | - Gordon W Laurie
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia, USA; Department of Ophthalmology, University of Virginia, Charlottesville, Virginia, USA; Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA.
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17
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Han JH, Cho YC, Koh WG, Choy YB. Preocular sensor system for concurrent monitoring of glucose levels and dry eye syndrome using tear fluids. PLoS One 2020; 15:e0239317. [PMID: 33027299 PMCID: PMC7540859 DOI: 10.1371/journal.pone.0239317] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 09/03/2020] [Indexed: 12/21/2022] Open
Abstract
The present study demonstrated a noninvasive preocular sensor system for the concurrent monitoring of diabetes and one of its prevalent complications, dry eye syndrome (DES), using tear fluids. Two distinct sensors, i.e., the glucose and DES sensors, were prepared and encased together in a single housing unit to produce the sensor system, and the tip was designed to be in contact with the eye surface noninvasively to collect and deliver tear fluid to the sensors. The glucose sensor was modified from a commercially available electrochemical sensor to allow for the measurement of glucose concentrations, even in a small amount of collected tear fluid. The DES sensor was equipped with a microchannel spaced with two parallel electrodes to determine the amount of collected tear fluid. In vivo experimental results revealed that with the collected tear fluid of about 0.6–1.0 μl, the sensor system estimated the blood glucose concentrations with acceptable accuracy compared with that of the glucometer in clinical use. The DES condition in animals was diagnosed with high sensitivity (91.7%) and specificity (83.3%).
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Affiliation(s)
- Jae Hoon Han
- Interdisciplinary Program in Bioengineering, College of Engineering, Seoul National University, Seoul, Korea
| | - Yong Chan Cho
- Interdisciplinary Program in Bioengineering, College of Engineering, Seoul National University, Seoul, Korea
| | - Won-Gun Koh
- Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul, Korea
| | - Young Bin Choy
- Interdisciplinary Program in Bioengineering, College of Engineering, Seoul National University, Seoul, Korea
- Institute of Medical & Biological Engineering, Medical Research Center, Seoul National University, Seoul, Korea
- Department of Biomedical Engineering, Seoul National University College of Medicine, Seoul, Korea
- * E-mail:
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18
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Yao YN, Di D, Yuan ZC, Wu L, Hu B. Schirmer Paper Noninvasive Microsampling for Direct Mass Spectrometry Analysis of Human Tears. Anal Chem 2020; 92:6207-6212. [PMID: 32250596 DOI: 10.1021/acs.analchem.9b05078] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Rapid and sensitive detection of metabolites and chemical residues in human tears is highly beneficial for understanding eye health. In this study, Schirmer paper was used for noninvasive microsampling of human tears, and then paper spray mass spectrometry (PSMS) was performed for direct analysis of human tears. Schirmer PSMS was successfully used for rapid diagnosis of dry-eye syndrome by detecting the volume and metabolites of human tears. Drugs of abuse, therapeutic drugs, and pharmacodynamics in human tears were also investigated by Schirmer PSMS. Furthermore, specific markers of environmental exposures in the air to human eyes, including volatile organic compounds, aerosol, and smoke, were unambiguously sampled and detected in human tears using Schirmer PSMS. Excellent analytical performances were achieved, including single-use, low-sample consumption (1.0 μL), rapid analysis (the whole analytical procedure completed within 3 min), high sensitivity (absolute limit of detection less than or equal to 0.5 pg, signal-to-noise ratio greater than or equal to 3), good reproducibility (relative standard deviation less than 10%, n = 3), and accurate quantitation (average deviation less than 3%, n = 3). Overall, our results showed that Schirmer PSMS is a highly effective method for direct tear analysis and is expected to be a convenient tool for human tear analysis in significant clinical applications.
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Affiliation(s)
- Ya-Nan Yao
- Institute of Mass Spectrometry and Atmospheric Environment, Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Jinan University, Guangzhou 510632, China
| | - Dandan Di
- Institute of Mass Spectrometry and Atmospheric Environment, Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Jinan University, Guangzhou 510632, China
| | - Zi-Cheng Yuan
- Institute of Mass Spectrometry and Atmospheric Environment, Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Jinan University, Guangzhou 510632, China
| | - Lin Wu
- Institute of Mass Spectrometry and Atmospheric Environment, Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Jinan University, Guangzhou 510632, China
| | - Bin Hu
- Institute of Mass Spectrometry and Atmospheric Environment, Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Jinan University, Guangzhou 510632, China
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19
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Nanoscale poly(acrylic acid)-based hydrogels prepared via a green single-step approach for application as low-viscosity biomimetic fluid tears. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2020; 110:110726. [PMID: 32204037 DOI: 10.1016/j.msec.2020.110726] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 12/16/2019] [Accepted: 02/03/2020] [Indexed: 12/19/2022]
Abstract
The present work reports a nanotechnology strategy to prepare a low-viscosity poly(acrylic acid) (PAAc)-based tear substitute with enhanced efficacy and compliance. Specifically, nanogels composed of PAAc and polyvinylpyrrolidone (PVP) were prepared by adapting an ionizing radiation method. For this purpose, different aqueous systems: PVP/PAAc nanoparticulate complexes, PVP/acrylic acid (AAc), N-vinylpyrrolidone (N-VP)/PAAc, and N-VP/AAc were exposed to gamma rays. The dynamic light scattering technique showed that stable nanogels are only produced in a relatively high yield from the PVP/AAc system. Nanogel formation was driven by the hydrogen-bonding complexation between PVP and PAAc (formed in situ) as well as the radiation-induced cross-linking. Transparency, viscosity and mucoadhesiveness of emerged nanogels were optimized by controlling the feed composition and irradiation dose. Furthermore, neutralized nanogels were topically applied in a dry eye model and compared with a PAAc-based commercial tear substitute, namely Vidisic® Gel. The results of Schirmer's test and tear break-up time demonstrated that nanogels prepared from AAc-rich feed solutions at 20 kGy enhanced markedly the dry eye conditions. The histopathological analysis also ensured the competence of PAAc-rich nanogels to completely return the corneal epithelium to its normal state.
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20
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Mastropasqua R, Agnifili L, Mastropasqua L. Structural and Molecular Tear Film Changes in Glaucoma. Curr Med Chem 2019; 26:4225-4240. [PMID: 30306854 DOI: 10.2174/0929867325666181009153212] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 07/13/2018] [Accepted: 09/19/2018] [Indexed: 12/31/2022]
Abstract
The Tear Film (TF) is a trilaminar and dynamic fluid covering the entire Ocular Surface (OS), consisting of a mucus, aqueous, and lipid layer deeply interacting between them. Because of its structure and functions, TF plays a pivotal role in the preservation of the OS integrity and the quality of vision. Medical therapy for glaucoma is recognized to profoundly disturb the OS homeostasis by altering all components of the ocular surface unit, including TF. The presence of preservatives, the number of daily eye drops instillations, and the duration of therapy are the main contributors to TF changes. From the physio-pathological side, TF alterations are induced by toxic and allergic mechanisms and result from goblet cell and Meibomian gland loss, dysfunction of accessory lacrimal glands, and epithelial disruption. In detail, TF changes are represented by mucus layer thinning, reduced mucin concentration, aqueous layer volume reduction, and lipid layer thinning with increased tear evaporation. Hyper- osmolarity and instability represent the main hallmarks of these changes and are an expression of a iatrogenic form of dry eye. TF undergoes also molecular modifications that primarily reflect a therapy- or disease-induced inflammatory status of the OS. Over the last years, this field of research aimed a progressively growing interest since molecular variations may be considered as potential candidate biomarkers of glaucoma. The aim of this review is to report the main TF changes occurring during glaucoma, exploring the relationship they may have with the glaucoma-related ocular surface disease and the patient quality of life, and their utility as potential biomarkers of disease.
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Affiliation(s)
| | - Luca Agnifili
- Ophthalmology Clinic, Department of Medicine and Aging Science, University G. d'Annunzio of Chieti-Pescara, Chieti, Italy
| | - Leonardo Mastropasqua
- Ophthalmology Clinic, Department of Medicine and Aging Science, University G. d'Annunzio of Chieti-Pescara, Chieti, Italy
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21
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Blackburn BJ, Jenkins MW, Rollins AM, Dupps WJ. A Review of Structural and Biomechanical Changes in the Cornea in Aging, Disease, and Photochemical Crosslinking. Front Bioeng Biotechnol 2019; 7:66. [PMID: 31019909 PMCID: PMC6459081 DOI: 10.3389/fbioe.2019.00066] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/07/2019] [Indexed: 12/27/2022] Open
Abstract
The study of corneal biomechanics is motivated by the tight relationship between biomechanical properties and visual function within the ocular system. For instance, variation in collagen fibril alignment and non-enzymatic crosslinks rank high among structural factors which give rise to the cornea's particular shape and ability to properly focus light. Gradation in these and other factors engender biomechanical changes which can be quantified by a wide variety of techniques. This review summarizes what is known about both the changes in corneal structure and associated changes in corneal biomechanical properties in aging, keratoconic, and photochemically crosslinked corneas. In addition, methods for measuring corneal biomechanics are discussed and the topics are related to both clinical studies and biomechanical modeling simulations.
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Affiliation(s)
- Brecken J. Blackburn
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of CWRU, Cleveland, OH, United States
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
| | - Michael W. Jenkins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH, United States
| | - Andrew M. Rollins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
| | - William J. Dupps
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
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22
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Glasgow BJ, Abduragimov AR. Ligand binding complexes in lipocalins: Underestimation of the stoichiometry parameter (n). BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 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] [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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23
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Kielkopf CS, Low JKK, Mok YF, Bhatia S, Palasovski T, Oakley AJ, Whitten AE, Garner B, Brown SHJ. Identification of a novel tetrameric structure for human apolipoprotein-D. J Struct Biol 2018; 203:205-218. [PMID: 29885491 DOI: 10.1016/j.jsb.2018.05.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 05/18/2018] [Accepted: 05/30/2018] [Indexed: 10/14/2022]
Abstract
Apolipoprotein-D is a 25 kDa glycosylated member of the lipocalin family that folds into an eight-stranded β-barrel with a single adjacent α-helix. Apolipoprotein-D specifically binds a range of small hydrophobic ligands such as progesterone and arachidonic acid and has an antioxidant function that is in part due to the reduction of peroxidised lipids by methionine-93. Therefore, apolipoprotein-D plays multiple roles throughout the body and is protective in Alzheimer's disease, where apolipoprotein-D overexpression reduces the amyloid-β burden in Alzheimer's disease mouse models. Oligomerisation is a common feature of lipocalins that can influence ligand binding. The native structure of apolipoprotein-D, however, has not been conclusively defined. Apolipoprotein-D is generally described as a monomeric protein, although it dimerises when reducing peroxidised lipids. Here, we investigated the native structure of apolipoprotein-D derived from plasma, breast cyst fluid (BCF) and cerebrospinal fluid. In plasma and cerebrospinal fluid, apolipoprotein-D was present in high-molecular weight complexes, potentially in association with lipoproteins. In contrast, apolipoprotein-D in BCF formed distinct oligomeric species. We assessed apolipoprotein-D oligomerisation using native apolipoprotein-D purified from BCF and a suite of complementary methods, including multi-angle laser light scattering, analytical ultracentrifugation and small-angle X-ray scattering. Our analyses showed that apolipoprotein-D predominantly forms a ∼95 to ∼100 kDa tetramer. Small-angle X-ray scattering analysis confirmed these findings and provided a structural model for apolipoprotein-D tetramer. These data indicate apolipoprotein-D rarely exists as a free monomer under physiological conditions and provide insights into novel native structures of apolipoprotein-D and into oligomerisation behaviour in the lipocalin family.
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Affiliation(s)
- Claudia S Kielkopf
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia; School of Biological Sciences, University of Wollongong, Wollongong, NSW, Australia; Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia.
| | - Jason K K Low
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia.
| | - Yee-Foong Mok
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, Australia.
| | - Surabhi Bhatia
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia; School of Biological Sciences, University of Wollongong, Wollongong, NSW, Australia.
| | - Tony Palasovski
- Illawarra and Shoalhaven Local Health District (ISLHD), Wollongong, NSW, Australia; Specialist Breast Clinic Sutherland Shire and Wollongong, NSW, Australia; Integrated Specialist Health Care Sutherland Shire, NSW, Australia
| | - Aaron J Oakley
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia; Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia; School of Chemistry, University of Wollongong, Wollongong, NSW, Australia.
| | - Andrew E Whitten
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia.
| | - Brett Garner
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia; School of Biological Sciences, University of Wollongong, Wollongong, NSW, Australia; Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia.
| | - Simon H J Brown
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia; School of Biological Sciences, University of Wollongong, Wollongong, NSW, Australia; Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia.
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Mateo Orobia AJ, Saa J, Ollero Lorenzo A, Herreras JM. Combination of hyaluronic acid, carmellose, and osmoprotectants for the treatment of dry eye disease. Clin Ophthalmol 2018; 12:453-461. [PMID: 29563769 PMCID: PMC5846763 DOI: 10.2147/opth.s157853] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Background Dry Eye Disease (DED) is a multifactorial disease, with a high prevalence, that can have a great impact on the quality of life of patients. The first step of treatment includes the use of lacrimal substitutes composed of polymers, possible to associate osmoprotectant agents to the lacrimal substitutes. The aim of this article is to analyze the properties of the combination of hyaluronic acid (HA), carmellose, and osmoprotectors (Optava Fusion®; Allergan, Inc., Irvine, CA, USA) on DED. General considerations on the use of artificial tears are also proposed. Methods A group of ophthalmologists, experts in the management of the ocular surface, analyzed different aspects related to DED; among them, the use of artificial tears in general and the properties of the combination of HA, carmellose, and osmoprotectors, in particular, were discussed. A review of the literature was carried out, which included different articles published in Spanish, English, and French until April 2017. Conclusions DED is a common chronic pathology that usually requires sustained treatment. In addition, the combination of HA, carmellose, and osmoprotectors has proven to be effective in the treatment of symptoms and signs of dry eye by the synergistic action of all its components. This review provides key elements to help ophthalmologists who begin in the management of DED.
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Affiliation(s)
- Antonio José Mateo Orobia
- Cornea and Ocular Surface Unit, Aragón Healthcare Research Institute (Instituto de Investigación Sanitaria de Aragón), Miguel Servet University Hospital, Zaragoza, Spain
| | - Jorge Saa
- Ophthalmology Department and Research Unit of Jove Hospital Foundation, Gijón, Spain
| | - Alberto Ollero Lorenzo
- Cornea and Ocular Surface Unit, Meixoeiro Hospital, Complejo Hospitalario Universitario de Vigo (CHUVI), Vigo, Spain
| | - José María Herreras
- Valladolid University Clinical Hospital, Valladolid, Spain.,University Institute of Applied Ophthalmobiology (IOBA [Instituto Universitario de Oftalmobiología Aplicada]). Miguel Delibes Campus, Paseo de Belén, Valladolid, Spain
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25
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Acar D, Molina-Martínez IT, Gómez-Ballesteros M, Guzmán-Navarro M, Benítez-Del-Castillo JM, Herrero-Vanrell R. Novel liposome-based and in situ gelling artificial tear formulation for dry eye disease treatment. Cont Lens Anterior Eye 2017; 41:93-96. [PMID: 29223649 DOI: 10.1016/j.clae.2017.11.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 11/22/2017] [Accepted: 11/28/2017] [Indexed: 11/16/2022]
Abstract
PURPOSE Artificial tears are widely used in the treatment of dry eye disease, although current formulations do not closely resemble natural tears. The purpose of this study was the design and characterization of a novel in situ gelling artificial tear formulation, containing both lipid and aqueous components, in order to resemble natural tears and replenish the tear film. METHODS Liposomes, containing phosphatidylcholine, cholesterol, vitamins A and E, were prepared by the thin-film hydration method. The aqueous phase of the formulation was comprised of gellan gum, hydroxypropyl methylcellulose, levocarnitine, electrolytes (sodium chloride and potassium chloride), trehalose, and borates. The artificial tear was characterized in terms of liposome size, pH, surface tension, and viscosity. In vitro tolerance studies were performed in a human epithelial carcinoma cell line (HeLa) and a murine macrophage cell line (J774). In vivo tolerance was assessed in rabbits. RESULTS Liposomes presented a unimodal distribution with a mean size of 200.1 ± 4.4 nm. The resulting surface tension was 53.4 ± 1.1 mN/m (at 33 °C) and the pH was 7.6 ± 0.1. The viscosity of the formulation presented a mean value of 4.0 ± 0.1 mPa s within the shear rate interval of 200-1000 s-1 at 33 °C. Cell viability remained higher than 90% in both cell lines. No discomfort or clinical signs were observed in rabbits. CONCLUSIONS The liposome-based and in situ gelling artificial tear formulation presented good tolerance and suitable properties for topical ophthalmic administration. It may be beneficial in the treatment of dry eye disease.
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Affiliation(s)
- Duygu Acar
- Department of Pharmacy and Pharmaceutical Technology, Faculty of Pharmacy, Complutense University of Madrid, Plaza Ramón y Cajal s/n, 28040 Madrid, Spain.
| | - Irene Teresa Molina-Martínez
- Department of Pharmacy and Pharmaceutical Technology, Faculty of Pharmacy, Complutense University of Madrid, Plaza Ramón y Cajal s/n, 28040 Madrid, Spain; Sanitary Research Institute of the San Carlos Clinical Hospital (IdISSC) and the Ocular Pathology National Net (OFTARED) of the Institute of Health Carlos III, Calle Profesor Martín Lagos, s/n, 28040 Madrid, Spain.
| | - Miguel Gómez-Ballesteros
- Department of Pharmacy and Pharmaceutical Technology, Faculty of Pharmacy, Complutense University of Madrid, Plaza Ramón y Cajal s/n, 28040 Madrid, Spain; Sanitary Research Institute of the San Carlos Clinical Hospital (IdISSC) and the Ocular Pathology National Net (OFTARED) of the Institute of Health Carlos III, Calle Profesor Martín Lagos, s/n, 28040 Madrid, Spain.
| | - Manuel Guzmán-Navarro
- Biomedical Sciences Department, Pharmacy and Pharmaceutical Technology Unit, Faculty of Pharmacy, University of Alcalá, Ctra. de Madrid-Barcelona (Autovía A2) Km. 33,600, 28805 Alcalá de Henares, Madrid, Spain.
| | - José Manuel Benítez-Del-Castillo
- Sanitary Research Institute of the San Carlos Clinical Hospital (IdISSC) and the Ocular Pathology National Net (OFTARED) of the Institute of Health Carlos III, Calle Profesor Martín Lagos, s/n, 28040 Madrid, Spain; Ocular Surface and Inflammation Unit, San Carlos Clinical Hospital, Calle Profesor Martín Lagos, s/n, 28040 Madrid, Spain.
| | - Rocío Herrero-Vanrell
- Department of Pharmacy and Pharmaceutical Technology, Faculty of Pharmacy, Complutense University of Madrid, Plaza Ramón y Cajal s/n, 28040 Madrid, Spain; Sanitary Research Institute of the San Carlos Clinical Hospital (IdISSC) and the Ocular Pathology National Net (OFTARED) of the Institute of Health Carlos III, Calle Profesor Martín Lagos, s/n, 28040 Madrid, Spain.
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26
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Leal J, Smyth HDC, Ghosh D. Physicochemical properties of mucus and their impact on transmucosal drug delivery. Int J Pharm 2017; 532:555-572. [PMID: 28917986 PMCID: PMC5744044 DOI: 10.1016/j.ijpharm.2017.09.018] [Citation(s) in RCA: 270] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Revised: 09/06/2017] [Accepted: 09/07/2017] [Indexed: 02/06/2023]
Abstract
Mucus is a selective barrier to particles and molecules, preventing penetration to the epithelial surface of mucosal tissues. Significant advances in transmucosal drug delivery have recently been made and have emphasized that an understanding of the basic structure, viscoelastic properties, and interactions of mucus is of great value in the design of efficient drug delivery systems. Mucins, the primary non-aqueous component of mucus, are polymers carrying a complex and heterogeneous structure with domains that undergo a variety of molecular interactions, such as hydrophilic/hydrophobic, hydrogen bonds and electrostatic interactions. These properties are directly relevant to the numerous mucin-associated diseases, as well as delivering drugs across the mucus barrier. Therefore, in this review we discuss regional differences in mucus composition, mucus physicochemical properties, such as pore size, viscoelasticity, pH, and ionic strength. These factors are also discussed with respect to changes in mucus properties as a function of disease state. Collectively, the review seeks to provide a state of the art roadmap for researchers who must contend with this critical barrier to drug delivery.
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Affiliation(s)
- Jasmim Leal
- Division of Molecular Pharmaceutics and Drug Delivery, College of Pharmacy, The University of Texas at Austin, 2409 University Ave., Austin, TX 78712, USA
| | - Hugh D C Smyth
- Division of Molecular Pharmaceutics and Drug Delivery, College of Pharmacy, The University of Texas at Austin, 2409 University Ave., Austin, TX 78712, USA
| | - Debadyuti Ghosh
- Division of Molecular Pharmaceutics and Drug Delivery, College of Pharmacy, The University of Texas at Austin, 2409 University Ave., Austin, TX 78712, USA.
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Affiliation(s)
- Adrian-Marie Philippe
- Laboratoire
Charles Coulomb, UMR 5221, Université de Montpellier and CNRS, 34095 Montpellier, France
| | - Luca Cipelletti
- Laboratoire
Charles Coulomb, UMR 5221, Université de Montpellier and CNRS, 34095 Montpellier, France
| | - Domenico Larobina
- Institute
for Polymers, Composites and Biomaterials, National Research Council of Italy, P.le E. Fermi 1, Naples, 80055 Portici, Italy
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Lipocalins Are Required for Apical Extracellular Matrix Organization and Remodeling in Caenorhabditis elegans. Genetics 2017; 207:625-642. [PMID: 28842397 DOI: 10.1534/genetics.117.300207] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 08/22/2017] [Indexed: 12/11/2022] Open
Abstract
A lipid and glycoprotein-rich apical extracellular matrix (aECM) or glycocalyx lines exposed membranes in the body, and is particularly important to protect narrow tube integrity. Lipocalins ("fat cups") are small, secreted, cup-shaped proteins that bind and transport lipophilic cargo and are often found in luminal or aECM compartments such as mammalian plasma, urine, or tear film. Although some lipocalins can bind known aECM lipids and/or matrix metalloproteinases, it is not known if and how lipocalins affect aECM structure due to challenges in visualizing the aECM in most systems. Here we show that two Caenorhabditiselegans lipocalins, LPR-1 and LPR-3, have distinct functions in the precuticular glycocalyx of developing external epithelia. LPR-1 moves freely through luminal compartments, while LPR-3 stably localizes to a central layer of the membrane-anchored glycocalyx, adjacent to the transient zona pellucida domain protein LET-653 Like LET-653 and other C. elegans glycocalyx components, these lipocalins are required to maintain the patency of the narrow excretory duct tube, and also affect multiple aspects of later cuticle organization. lpr-1 mutants cannot maintain a continuous excretory duct apical domain and have misshapen cuticle ridges (alae) and abnormal patterns of cuticular surface lipid staining. lpr-3 mutants cannot maintain a passable excretory duct lumen, properly degrade the eggshell, or shed old cuticle during molting, and they lack cuticle barrier function. Based on these phenotypes, we infer that both LPR-1 and LPR-3 are required to build a properly organized aECM, while LPR-3 additionally is needed for aECM clearance and remodeling. The C. elegans glycocalyx provides a powerful system, amenable to both genetic analysis and live imaging, for investigating how lipocalins and lipids affect aECM structure.
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Bron AJ, de Paiva CS, Chauhan SK, Bonini S, Gabison EE, Jain S, Knop E, Markoulli M, Ogawa Y, Perez V, Uchino Y, Yokoi N, Zoukhri D, Sullivan DA. TFOS DEWS II pathophysiology report. Ocul Surf 2017; 15:438-510. [PMID: 28736340 DOI: 10.1016/j.jtos.2017.05.011] [Citation(s) in RCA: 975] [Impact Index Per Article: 139.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 05/26/2017] [Indexed: 12/18/2022]
Abstract
The TFOS DEWS II Pathophysiology Subcommittee reviewed the mechanisms involved in the initiation and perpetuation of dry eye disease. Its central mechanism is evaporative water loss leading to hyperosmolar tissue damage. Research in human disease and in animal models has shown that this, either directly or by inducing inflammation, causes a loss of both epithelial and goblet cells. The consequent decrease in surface wettability leads to early tear film breakup and amplifies hyperosmolarity via a Vicious Circle. Pain in dry eye is caused by tear hyperosmolarity, loss of lubrication, inflammatory mediators and neurosensory factors, while visual symptoms arise from tear and ocular surface irregularity. Increased friction targets damage to the lids and ocular surface, resulting in characteristic punctate epithelial keratitis, superior limbic keratoconjunctivitis, filamentary keratitis, lid parallel conjunctival folds, and lid wiper epitheliopathy. Hybrid dry eye disease, with features of both aqueous deficiency and increased evaporation, is common and efforts should be made to determine the relative contribution of each form to the total picture. To this end, practical methods are needed to measure tear evaporation in the clinic, and similarly, methods are needed to measure osmolarity at the tissue level across the ocular surface, to better determine the severity of dry eye. Areas for future research include the role of genetic mechanisms in non-Sjögren syndrome dry eye, the targeting of the terminal duct in meibomian gland disease and the influence of gaze dynamics and the closed eye state on tear stability and ocular surface inflammation.
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Affiliation(s)
- Anthony J Bron
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; Vision and Eye Research Unit, Anglia Ruskin University, Cambridge, UK.
| | - Cintia S de Paiva
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, USA
| | - Sunil K Chauhan
- Schepens Eye Research Institute & Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Stefano Bonini
- Department of Ophthalmology, University Campus Biomedico, Rome, Italy
| | - Eric E Gabison
- Department of Ophthalmology, Fondation Ophtalmologique Rothschild & Hôpital Bichat Claude Bernard, Paris, France
| | - Sandeep Jain
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Erich Knop
- Departments of Cell and Neurobiology and Ocular Surface Center Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Maria Markoulli
- School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
| | - Yoko Ogawa
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Victor Perez
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami, Miami, FL, USA
| | - Yuichi Uchino
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Norihiko Yokoi
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Driss Zoukhri
- Tufts University School of Dental Medicine, Boston, MA, USA
| | - David A Sullivan
- Schepens Eye Research Institute & Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
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Abstract
The members of the Tear Film Subcommittee reviewed the role of the tear film in dry eye disease (DED). The Subcommittee reviewed biophysical and biochemical aspects of tears and how these change in DED. Clinically, DED is characterized by loss of tear volume, more rapid breakup of the tear film and increased evaporation of tears from the ocular surface. The tear film is composed of many substances including lipids, proteins, mucins and electrolytes. All of these contribute to the integrity of the tear film but exactly how they interact is still an area of active research. Tear film osmolarity increases in DED. Changes to other components such as proteins and mucins can be used as biomarkers for DED. The Subcommittee recommended areas for future research to advance our understanding of the tear film and how this changes with DED. The final report was written after review by all Subcommittee members and the entire TFOS DEWS II membership.
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31
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Sterner O, Karageorgaki C, Zürcher M, Zürcher S, Scales CW, Fadli Z, Spencer ND, Tosatti SGP. Reducing Friction in the Eye: A Comparative Study of Lubrication by Surface-Anchored Synthetic and Natural Ocular Mucin Analogues. ACS APPLIED MATERIALS & INTERFACES 2017; 9:20150-20160. [PMID: 28561563 DOI: 10.1021/acsami.6b16425] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Biomaterials used in the ocular environment should exhibit specific tribological behavior to avoid discomfort and stress-induced epithelial damage during blinking. In this study, two macromolecules that are commonly employed as ocular biomaterials, namely, poly(vinylpyrrolidone) (PVP) and hyaluronan (HA), are compared with two known model glycoproteins, namely bovine submaxillary mucin (BSM) and α1-acid glycoprotein (AGP), with regard to their nonfouling efficiency, wettability, and tribological properties when freely present in the lubricant, enabling spontaneous adsorption, and when chemisorbed under low contact pressures. Chemisorbed coatings were prepared by means of photochemically triggered nitrene insertion reactions. BSM and AGP provided boundary lubrication when spontaneously adsorbed in a hydrophobic contact with a coefficient of friction (CoF) of ∼0.03-0.04. PVP and HA were found to be excellent boundary lubricants when chemisorbed (CoF ≤ 0.01). Notably, high-molecular-weight PVP generated thick adlayers, typically around 14 nm, and was able to reduce the CoF below 0.005 when slid against a BSM-coated poly(dimethylsiloxane) pin in a tearlike fluid.
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Affiliation(s)
- Olof Sterner
- SuSoS AG , Lagerstrasse 14, CH-8006 Dübendorf, Switzerland
| | | | | | - Stefan Zürcher
- SuSoS AG , Lagerstrasse 14, CH-8006 Dübendorf, Switzerland
- Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich , Vladimir-Prelog-Weg 5, CH-8093 Zurich, Switzerland
| | - Charles W Scales
- Johnson & Johnson Vision Care Inc. , Jacksonville, Florida 32256, United States
| | - Zohra Fadli
- Johnson & Johnson Vision Care Inc. , Jacksonville, Florida 32256, United States
| | - Nicholas D Spencer
- Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich , Vladimir-Prelog-Weg 5, CH-8093 Zurich, Switzerland
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Accounting for Ethnicity-Related Differences in Ocular Surface Integrity as a Step Toward Understanding Contact Lens Discomfort. Eye Contact Lens 2017; 43:23-31. [PMID: 27763911 DOI: 10.1097/icl.0000000000000342] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Contact lens discomfort is a common problem that can lead to unsuccessful or limited contact lens wear. Although many factors may contribute to contact lens discomfort, limited research has explored the influence of ethnicity-related differences in the anatomy and physiology of the ocular surface. Therefore, we performed a search of the literature in PubMed using key words related to "ocular surface" paired with the terms "race" and "ethnicity." The goal of this review was to determine potential areas of research regarding ethnicity differences, particularly between Asian and non-Asian eyes, in ocular surface integrity to advance our understanding of contact lens discomfort.
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Pu P, Stone CE, Burdick JT, Murray JI, Sundaram MV. The Lipocalin LPR-1 Cooperates with LIN-3/EGF Signaling To Maintain Narrow Tube Integrity in Caenorhabditis elegans. Genetics 2017; 205:1247-1260. [PMID: 28040739 PMCID: PMC5340336 DOI: 10.1534/genetics.116.195156] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 12/21/2016] [Indexed: 11/18/2022] Open
Abstract
Lipocalins are secreted cup-shaped glycoproteins that bind sterols, fatty acids, and other lipophilic molecules. Lipocalins have been implicated in a wide array of processes related to lipophilic cargo transport, sequestration, and signaling, and several are used as biomarkers for human disease, but the functions of most lipocalins remain poorly understood. Here we show that the Caenorhabditis elegans lipocalin LPR-1 is required to maintain apical membrane integrity and a continuous lumen in two narrow unicellular tubes, the excretory duct and pore, during a period of rapid lumen elongation. LPR-1 fusion protein is expressed by the duct and pore and accumulates both intracellularly and in apical extracellular compartments, but it can also function cell nonautonomously when provided from outside of the excretory system. lpr-1 mutant defects can be rescued by increased signaling through the epidermal growth factor (EGF)-Ras-extracellular signal regulated kinase (ERK) pathway, which promotes the more elongated duct vs. less elongated pore tube fate. Spatial and temporal rescue experiments indicate that Ras signaling acts within the duct and pore tubes during or prior to cell fate determination to bypass the requirement for LPR-1 lpr-1 mutations did not disrupt LIN-3/EGF-dependent duct-fate specification, prevent functioning of any specific LIN-3/EGF isoform, or alter LET-23/EGFR localization, and reduced signaling did not phenocopy or enhance lpr-1 mutant defects. These data suggest that LPR-1 protects lumen integrity through a LIN-3/EGF-independent mechanism, but that increased signaling upregulates some target(s) that can compensate for lpr-1 absence.
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Affiliation(s)
- Pu Pu
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Craig E Stone
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Joshua T Burdick
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - John I Murray
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Meera V Sundaram
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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Phan CM, Bajgrowicz-Cieslak M, Subbaraman LN, Jones L. Release of Moxifloxacin from Contact Lenses Using an In Vitro Eye Model: Impact of Artificial Tear Fluid Composition and Mechanical Rubbing. Transl Vis Sci Technol 2016; 5:3. [PMID: 27847690 PMCID: PMC5106195 DOI: 10.1167/tvst.5.6.3] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Accepted: 09/10/2016] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The aim of this study was to evaluate and compare the release of moxifloxacin from a variety of daily disposable (DD) contact lenses (CLs) under various conditions using a novel in vitro eye model. METHODS Four commercially available DD conventional hydrogel (CH) CLs (nelfilcon A, omafilcon A, etafilcon A, and ocufilcon B) and three silicone hydrogel (SH) CLs (somofilcon A, narafilcon A, and delefilcon A) were evaluated. These lenses were incubated in moxifloxacin for 24 hours. The release of the drug was measured using a novel in vitro model in three experimental conditions: (1) phosphate buffered saline (PBS); (2) artificial tear solution (ATS) containing a variety of proteins and lipids; and (3) ATS with mechanical rubbing produced by the device. RESULTS Overall, CH CLs had a higher drug release than SH CLs (P < 0.05) under all conditions. Typically, a higher drug release was observed in PBS than ATS (P < 0.05). For CH, drug release was found to be higher in ATS with rubbing than PBS or ATS (P < 0.05). For most lens types, ATS with rubbing produced higher drug release than ATS alone (P < 0.05). Generally, the release kinetics for all conditions were sustained over the 24-hour testing period, and no burst release was observed (P < 0.05). CONCLUSIONS Moxifloxacin release from a CL into ATS is lower when compared to release into PBS. When mechanical rubbing is introduced, the amount of drugs released is increased. TRANSLATIONAL RELEVANCE Results suggest that sophisticated in vitro models are necessary to adequately model on-eye drug release from CL materials.
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Affiliation(s)
- Chau-Minh Phan
- Centre for Contact Lens Research, School of Optometry and Vision Science, Waterloo, Ontario, Canada
| | - Magdalena Bajgrowicz-Cieslak
- Department of Mechanics, Material Science and Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Lakshman N. Subbaraman
- Centre for Contact Lens Research, School of Optometry and Vision Science, Waterloo, Ontario, Canada
| | - Lyndon Jones
- Centre for Contact Lens Research, School of Optometry and Vision Science, Waterloo, Ontario, Canada
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Gronkiewicz KM, Giuliano EA, Sharma A, Mohan RR. Effects of topical hyaluronic acid on corneal wound healing in dogs: a pilot study. Vet Ophthalmol 2016; 20:123-130. [DOI: 10.1111/vop.12379] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Kristina M. Gronkiewicz
- Veterinary Medicine and Surgery; University of Missouri; Columbia, 900 East Campus Drive MO 65211 USA
| | - Elizabeth A. Giuliano
- Veterinary Medicine and Surgery; University of Missouri; Columbia, 900 East Campus Drive MO 65211 USA
| | - Ajay Sharma
- Veterinary Medicine and Surgery; University of Missouri; Columbia, 900 East Campus Drive MO 65211 USA
- Harry S. Truman Memorial Veteran Hospital; Columbia MO USA
| | - Rajiv R. Mohan
- Veterinary Medicine and Surgery; University of Missouri; Columbia, 900 East Campus Drive MO 65211 USA
- Harry S. Truman Memorial Veteran Hospital; Columbia MO USA
- Mason Eye Institute; School of Medicine; Columbia MO USA
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Spontaneous Blinking from a Tribological Viewpoint. Ocul Surf 2015; 13:236-49. [DOI: 10.1016/j.jtos.2014.12.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 12/27/2014] [Accepted: 12/01/2014] [Indexed: 11/24/2022]
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Abstract
The interplay of different structures belonging to either the anterior segment of the eye or its accessory visual apparatus, which all share common embryological, anatomical, functional, and physiological features, is discussed. Explanation of such terms, as ocular surface, lacrimal functional unit, and ocular surface system, is provided.
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Affiliation(s)
- T N Safonova
- Research Institute of Eye Diseases, 11 A, B, Rossolimo St., Moscow, Russian Federation, 119021
| | - L S Pateyuk
- Research Institute of Eye Diseases, 11 A, B, Rossolimo St., Moscow, Russian Federation, 119021
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38
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Vasquez PA, Forest MG. Complex Fluids and Soft Structures in the Human Body. COMPLEX FLUIDS IN BIOLOGICAL SYSTEMS 2015. [DOI: 10.1007/978-1-4939-2065-5_2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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39
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Interfacial Phenomena and the Ocular Surface. Ocul Surf 2014; 12:178-201. [DOI: 10.1016/j.jtos.2014.01.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Revised: 01/06/2014] [Accepted: 01/21/2014] [Indexed: 01/07/2023]
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Saraygord-Afshari N, Naderi-Manesh H, Naderi M. Enhanced reproducibility of the human gel-based tear proteome maps in the presence of di-(2-hydroxyethyl) disulfide. Biotechnol Appl Biochem 2014; 61:660-7. [PMID: 24575874 DOI: 10.1002/bab.1221] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 02/21/2014] [Indexed: 11/06/2022]
Affiliation(s)
- Neda Saraygord-Afshari
- Department of Biophysics; Faculty of Biological Sciences; Tarbiat Modares University; Tehran Iran
| | - Hossein Naderi-Manesh
- Department of Biophysics; Faculty of Biological Sciences; Tarbiat Modares University; Tehran Iran
| | - Mostafa Naderi
- Bina Eye Hospital; Tehran Iran
- Department of Ophthalmology; Baqiyatallah University of Medical Sciences; Tehran Iran
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Hesselink RW, Findlay JBC. Expression, characterization and ligand specificity of lipocalin-1 interacting membrane receptor (LIMR). Mol Membr Biol 2014; 30:327-37. [PMID: 23964685 DOI: 10.3109/09687688.2013.823018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Human lipocalin-1 interacting membrane receptor (LIMR) was the first lipocalin receptor to be identified, as a specific receptor for lipocalin-1 (Lcn1). Subsequently LIMR has been reported to interact with other ligands as well, notably with the bovine lipocalin β-lactoglobulin (BLG) and with the unrelated secretoglobin uteroglobin (UG). To study the ligand-binding behaviour of this prototypic lipocalin receptor in more detail, a system was developed for the recombinant expression of LIMR in Drosophila Schneider 2 (S2) cells, and for the subsequent solubilization and purification of the protein. The receptor forms dimers or larger oligomers when solubilized in n-dodecyl β-D-maltoside (DDM). The full-length, functional receptor was captured onto a surface plasmon resonance (SPR) chip via an α-V5 antibody, and the binding of various potential ligands was followed in time. In this way, LIMR was shown to be highly specific for Lcn1, binding the lipocalin with low micromolar to high nanomolar affinity. No interactions with any of the other putative ligands could be detected, raising doubts about the physiological relevance of the reported binding of BLG and UG to the receptor.
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Tibrewal S, Sarkar J, Jassim SH, Gandhi S, Sonawane S, Chaudhary S, Byun YS, Ivanir Y, Hallak J, Horner JH, Newcomb M, Jain S. Tear fluid extracellular DNA: diagnostic and therapeutic implications in dry eye disease. Invest Ophthalmol Vis Sci 2013; 54:8051-61. [PMID: 24255046 DOI: 10.1167/iovs.13-12844] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
PURPOSE To determine the abundance of extracellular DNA (eDNA) in tear fluid of patients with dry eye disease (DED) and to report clinical outcomes after DNase I eyedrops use to reduce excessive tear fluid eDNA. METHODS Tear fluid was collected from healthy control subjects and patients with DED. The eDNA abundance was determined with the PicoGreen dye assay. The DED symptoms and clinical signs were recorded and correlated with eDNA abundance. Two patients with DED having excessive eDNA in tear fluid were treated with DNase I eyedrops. RESULTS The PicoGreen dye assay measures tear fluid eDNA abundance after a 2-minute incubation time. With longer incubations, admixed cells also contribute to eDNA measurements. The mean (SE) eDNA abundance in healthy control subjects' tear fluid was 1.4 (0.2) μg/mL. The mean (SE) eDNA abundance in tear fluid of patients with nonautoimmune DED, autoimmune DED, and graft versus host disease was significantly higher: the values were 2.9 (0.6), 5.2 (1.2), and 9.1 (2.3) μg/mL, respectively (P < 0.05). In most of these patients, the PicoGreen dye kinetic assay of tear fluid showed an increase in fluorescence signal due to the presence of viable cells in tear fluid. Tear fluid eDNA had the best correlation with corneal Rose Bengal staining (r = 0.55). Treatment of patients having DED with DNase I eyedrops reduced eDNA abundance, abrogated signal increase, and improved comfort. CONCLUSIONS Excessive eDNA is present in tear fluid of patients with dry eyes. A novel therapeutic approach for managing DED may be to measure eDNA abundance in tear fluid with the PicoGreen dye assay and reduce excessive amounts with DNase I eyedrops.
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Affiliation(s)
- Sapna Tibrewal
- Corneal Neurobiology Laboratory, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, College of Medicine, Chicago, Illinois
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Physico-chemical properties of different forms of bovine lactoferrin. Food Chem 2013; 141:3007-13. [DOI: 10.1016/j.foodchem.2013.05.139] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 05/20/2013] [Accepted: 05/30/2013] [Indexed: 11/16/2022]
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Li WY, Hsiao C, Graham AD, Lin MC. Corneal epithelial permeability: ethnic differences between Asians and non-Asians. Cont Lens Anterior Eye 2013; 36:215-8. [PMID: 23507503 DOI: 10.1016/j.clae.2013.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Revised: 01/22/2013] [Accepted: 02/18/2013] [Indexed: 12/17/2022]
Abstract
PURPOSE To ascertain whether a difference in the permeability of the corneal epithelium to fluorescein (Pdc) exists between Asians and non-Asians. METHODS From a multi-study database we extracted 632 records of baseline, open-eye Pdc measurements taken on both eyes of 176 subjects. Subjects were awake for a minimum of 4h before measurement, and were free of ocular disease and central corneal staining. Pdc was transformed by natural logarithm to better approximate normality for statistical tests. RESULTS The mean ln(Pdc) in the Asian group was significantly greater than in the non-Asian group [-2.34 ln(nm/s) vs. -2.58 ln(nm/s); p<0.001]. CONCLUSIONS Compared with non-Asians, Asians exhibited a less negative ln(Pdc), which translates to a higher Pdc and a more permeable corneal epithelium. We speculate that this may be related to anatomic differences responsible for greater eyelid tension in Asians.
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Affiliation(s)
- Wing Y Li
- Clinical Research Center, School of Optometry, University of California, Berkeley, CA, USA
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Pires NR, Cunha PL, Maciel JS, Angelim AL, Melo VM, de Paula RC, Feitosa JP. Sulfated chitosan as tear substitute with no antimicrobial activity. Carbohydr Polym 2013; 91:92-9. [DOI: 10.1016/j.carbpol.2012.08.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 08/02/2012] [Accepted: 08/03/2012] [Indexed: 10/28/2022]
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Leiske DL, Miller CE, Rosenfeld L, Cerretani C, Ayzner A, Lin B, Meron M, Senchyna M, Ketelson HA, Meadows D, Srinivasan S, Jones L, Radke CJ, Toney MF, Fuller GG. Molecular structure of interfacial human meibum films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:11858-11865. [PMID: 22783994 DOI: 10.1021/la301321r] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Meibum is the primary component of the tear film lipid layer. Thought to play a role in tear film stabilization, understanding the physical properties of meibum and how they change with disease will be valuable in identifying dry eye treatment targets. Grazing incidence X-ray diffraction and X-ray reflectivity were applied to meibum films at an air-water interface to identify molecular organization. At room temperature, interfacial meibum films formed two coexisting scattering phases with rectangular lattices and next-nearest neighbor tilts, similar to the Ov phase previously identified in fatty acids. The intensity of the diffraction peaks increased with compression, although the lattice spacing and molecular tilt angle remained constant. Reflectivity measurements at surface pressures of 18 mN/m and above revealed multilayers with d-spacings of 50 Å, suggesting that vertical organization rather than lateral was predominantly affected by meibum-film compression.
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Affiliation(s)
- Danielle L Leiske
- Chemical Engineering Department, Stanford University, California, USA
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Millar TJ, King-Smith PE. Analysis of Comparison of Human Meibomian Lipid Films and Mixtures with Cholesteryl Esters In Vitro Films using High Resolution Color Microscopy. Invest Ophthalmol Vis Sci 2012; 53:4710-9. [PMID: 22695957 DOI: 10.1167/iovs.12-10022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
PURPOSE The lipid layer of the tears has been studied in vivo using high resolution color microscopy (HRCM). The purpose of these experiments was to gain further insight into the structure of the lipid layer by applying HRCM to in vitro meibomian lipid films. METHODS Films of human meibomian lipids, cholesteryl nervonate, cholesteryl palmitate, or their mixtures, were spread on a Langmuir trough. Changes to the films were monitored using HRCM as the films were compressed to different surface pressures. The penetration of albumin into a meibomian lipid film also was studied. RESULTS Small amounts of meibomian lipids at low pressures formed very thin films estimated to be 5.2 nm thick. Compression caused spots to appear in the films. At higher concentrations, micro lenses were a feature of the film. Cholesteryl nervonate formed a multilayered oil slick that did not change with surface pressure. Cholesteryl palmitate formed a stiff film that collapsed at high compression. Mixtures of cholesteryl nervonate and meibomian lipids showed that they mixed to increase surface pressures above that of the individual components. HRCM also allowed albumin to be seen penetrating the meibomian lipid film. CONCLUSIONS HRCM combined with in vitro surface pressure measurements using a Langmuir trough is useful for modeling meibomian lipid films. The films often resemble the appearance of the lipid layer of in vivo films. The data indicate that the lipid layer might be modeled best as a duplex film containing an array of liquid crystals.
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Affiliation(s)
- Thomas J Millar
- University of Western Sydney, School of Science and Health, Penrith, New South Wales, Australia.
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Abstract
Lipocalins are a family of diverse low molecular weight proteins that act extracellularly. They use multiple recognition properties that include 1) ligand binding to small hydrophobic molecules, 2) macromolecular complexation with other soluble macromolecules, and 3) binding to specific cell surface receptors to deliver cargo. Tear lipocalin (TLC) is a major protein in tears and has a large ligand-binding cavity that allows the lipocalin to bind an extensive and diverse set of lipophilic molecules. TLC can also bind to macromolecules, including the tear proteins lactoferin and lysozyme. The receptor to which TLC binds is termed tear lipocalin-interacting membrane receptor (LIMR). LIMR appears to work by endocytosis. TLC has a variety of suggested functions in tears, including regulation of tear viscosity, binding and release of lipids, endonuclease inactivation of viral DNA, binding of microbial siderophores (iron chelators used to deliver essential iron to bacteria), serving as a biomarker for dry eye, and possessing anti-inflammatory activity. Additional research is warranted to determine the actual functions of TLC in tears and the presence of its receptor on the ocular surface.
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Affiliation(s)
- Darlene A Dartt
- Schepens Eye Research Institute and Harvard Medical School, Boston, MA 02114, USA.
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Nordgård CT, Draget KI. Oligosaccharides As Modulators of Rheology in Complex Mucous Systems. Biomacromolecules 2011; 12:3084-90. [DOI: 10.1021/bm200727c] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Catherine Taylor Nordgård
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology, NTNU, 7491 Trondheim, Norway
| | - Kurt I. Draget
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology, NTNU, 7491 Trondheim, Norway
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