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Schweitzer D, Haueisen J, Klemm M. Suppression of natural lens fluorescence in fundus autofluorescence measurements: review of hardware solutions. BIOMEDICAL OPTICS EXPRESS 2022; 13:5151-5170. [PMID: 36425615 PMCID: PMC9664869 DOI: 10.1364/boe.462559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/25/2022] [Accepted: 07/25/2022] [Indexed: 06/16/2023]
Abstract
Fluorescence lifetime imaging ophthalmoscopy (FLIO), a technique for investigating metabolic changes in the eye ground, can reveal the first signs of diseases related to metabolism. The fluorescence of the natural lens overlies the fundus fluorescence. Although the influence of natural lens fluorescence can be somewhat decreased with mathematical models, excluding this influence during the measurement by using hardware enables more exact estimation of the fundus fluorescence. Here, we analyze four 1-photon excitation hardware solutions to suppress the influence of natural lens fluorescence: aperture stop separation, confocal scanning laser ophthalmoscopy, combined confocal scanning laser ophthalmoscopy and aperture stop separation, and dual point confocal scanning laser ophthalmoscopy. The effect of each principle is demonstrated in examples. The best suppression is provided by the dual point principle, realized with a confocal scanning laser ophthalmoscope. In this case, in addition to the fluorescence of the whole eye, the fluorescence of the anterior part of the eye is detected from a non-excited spot of the fundus. The intensity and time-resolved fluorescence spectral data of the fundus are derived through the subtraction of the simultaneously measured fluorescence of the excited and non-excited spots. Advantages of future 2-photon fluorescence excitation are also discussed. This study provides the first quantitative evaluation of hardware principles to suppress the fluorescence of the natural lens during measurements of fundus autofluorescence.
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Affiliation(s)
- D. Schweitzer
- Department of Ophthalmology, University Hospital Jena, Am Klinikum 1, 07747 Jena, Germany
| | - J. Haueisen
- Institute of Biomedical Engineering and Informatics, POB 100565, 98694 Ilmenau, Germany
| | - M. Klemm
- Institute of Biomedical Engineering and Informatics, POB 100565, 98694 Ilmenau, Germany
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Karumanchi DK, Gaillard ER, Dillon J. Early Diagnosis of Diabetes through the Eye. Photochem Photobiol 2015; 91:1497-504. [DOI: 10.1111/php.12524] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 08/10/2015] [Indexed: 12/24/2022]
Affiliation(s)
| | - Elizabeth R. Gaillard
- Department of Chemistry and Biochemistry; Northern Illinois University; DeKalb IL
- Department of Biology; Northern Illinois University; DeKalb IL
| | - James Dillon
- Department of Chemistry and Biochemistry; Northern Illinois University; DeKalb IL
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Rubio N, Martínez-Junza V, Estruga J, Borrell JI, Mora M, Sagristá ML, Nonell S. Ground- and excited-state interactions of 2,7,12,17-tetraphenylporphycene with model target biomolecules for type-I photodynamic therapy. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424609000103] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Biosubstrate-sensitizer binding is one of the factors that enhances the type-I mechanism over the type-II in the whole photodynamic process. 2,7,12,17-Tetraphenylporphycene (TPPo), a second-generation photosensitizer, is a hydrophobic compound with good photophysical properties for photodynamic therapy applications that has proved its ability for the photoinactivation of different cell lines. Nevertheless, little is known about its mechanism of action. This paper focuses on the study of the interaction/binding of TPPo with different model biomolecules that may favor the type-I mechanism in the overall photodynamic process, including nucleosides, proteins, and phospholipids. Compared with more hydrophilic photosensitizers, it is concluded that TPPo is more likely to undergo type-II (singlet oxygen) than type-I (electron transfer) photodynamic processes in biological environments.
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Affiliation(s)
- Noemí Rubio
- Grup d'Enginyeria Molecular, Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain
| | - Víctor Martínez-Junza
- Grup d'Enginyeria Molecular, Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain
| | - Jordi Estruga
- Grup d'Enginyeria Molecular, Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain
| | - José I. Borrell
- Grup d'Enginyeria Molecular, Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain
| | - Margarita Mora
- Departament de Bioquímica i Biología Molecular, Facultat de Biologia, Universitat de Barcelona, Avinguda Diagonal 645, 08028 Barcelona, Spain
| | - M. Lluïsa Sagristá
- Departament de Bioquímica i Biología Molecular, Facultat de Biologia, Universitat de Barcelona, Avinguda Diagonal 645, 08028 Barcelona, Spain
| | - Santi Nonell
- Grup d'Enginyeria Molecular, Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain
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Ehrenshaft M, Zhao B, Andley UP, Mason RP, Roberts JE. Immunological detection of N-formylkynurenine in porphyrin-mediated photooxided lens α-crystallin. Photochem Photobiol 2011; 87:1321-9. [PMID: 21770952 PMCID: PMC3598576 DOI: 10.1111/j.1751-1097.2011.00979.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Crystallin proteins are responsible for maintaining lens transparency and allowing the lens to focus light undistorted onto the retina. The α-crystallins are the major lens crystallins, and function as both structural proteins and chaperones to protect all lens proteins from damage leading to lens deterioration. Because lens crystallin proteins do not turn over, the damage they accumulate can lead to cataracts, the world's leading cause of blindness. Photosensitizing porphyrins can accumulate in the eye through either endogenous metabolism or through therapeutic or diagnostic procedures. Porphyrin buildup exacerbates lens aging through increased levels of singlet oxygen, resulting in protein polymerization and amino acid residue alteration. Tryptophans oxidize to kynurenine and N-formylkynurenine (NFK) causing irreversible changes in the refractive index of the normally transparent lens, leading to development of cataracts. Additionally, NFK is itself a photosensitizer, and its presence exacerbates lens deterioration. This work uses anti-NFK antiserum to study porphyrin-facilitated photooxidation of α-crystallin tryptophan residues. In vitro experiments show that four biologically interesting porphyrins mediate α-crystallin polymerization and accumulation of both protein radicals and NFK. Confocal microscopy of cultured human lens epithelial cells indicates that while all four porphyrins photosensitize cellular proteins, not all oxidize the tryptophans of cellular α-crystallin to NFK.
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Affiliation(s)
- Marilyn Ehrenshaft
- Laboratory of Pharmacology and Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA.
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Mukherjee P, Bose S, Hurd AA, Adhikary R, Schönenbrücher H, Hamir AN, Richt JA, Casey TA, Rasmussen MA, Petrich JW. Monitoring the accumulation of lipofuscin in aging murine eyes by fluorescence spectroscopy. Photochem Photobiol 2008; 85:234-8. [PMID: 18764899 DOI: 10.1111/j.1751-1097.2008.00425.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The integrated fluorescence of murine eyes is collected as a function of age. This fluorescence is attributed to pigments generally referred to as lipofuscin and is observed to increase with age. No difference in fluorescence intensity is observed between the eyes of males or females. This work provides a benchmark for further studies that are planned in order to use such signatures as markers of central nervous system (CNS) tissue or even of diseased CNS tissue and provides a basis for determining the age of a healthy animal.
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Aveline BM, Sattler RM, Redmond RW. Environmental Effects on Cellular Photosensitization: Correlation of Phototoxicity Mechanism with Transient Absorption Spectroscopy Measurements. Photochem Photobiol 1998. [DOI: 10.1111/j.1751-1097.1998.tb03252.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Borissevitch IE, Gandini SC. Photophysical studies of excited-state characteristics of meso-tetrakis (4-N-methyl-pyridiniumyl) porphyrin bound to DNA. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 1998; 43:112-20. [PMID: 9679313 DOI: 10.1016/s1011-1344(98)00093-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The interaction of meso-tetrakis (4-N-methyl-pyridiniumyl) porphyrin (TMPyP) with DNA has been investigated at ionic strength (IS) values of 0.01 and 0.20 M (pH 6.8) using the flash-photolysis technique along with optical absorption and fluorescence data. It is found that the aggregation of TMPyP observed at the porphyrin excess reduces its total fluorescence intensity (JT) and the T-T absorption. At low IS the JT and the T-T absorption for the TMPyP monomers bound to the GC DNA sites are lower than those for the free ones, whereas binding to the AT sites (high IS) increases JT. At low IS the triplet decay of TMPyP is mono-exponential, the lifetime increasing with the [DNA] increase, while at high IS the addition of DNA transforms this profile to a bi-exponential form with lifetimes of the components independent of [DNA]. Binding to DNA reduces the quenching constants of the porphyrin triplet states by molecular oxygen (kq), the effect depending on the site and mode of binding. So, at low IS the kq value for the TMPyP externally bound to the GC sites (3.0 x 10(8) M-1 s-1) is five times lower than that for the free porphyrin and twice as high as that for the intercalated one. At high IS the TMPyP binding reduces the kq three-fold for the AT sites in the minor groove and 16-fold in the major groove as compared with the free one (approximately or equal to 1.6 x 10(9) M-1 s-1).
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Borissevitch IE, Tominaga TT, Schmitt CC. Photophysical studies on the interaction of two water-soluble porphyrins with bovine serum albumin. Effects upon the porphyrin triplet state characteristics. J Photochem Photobiol A Chem 1998. [DOI: 10.1016/s1010-6030(98)00216-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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