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Age-dependent photoionization thresholds of melanosomes and lipofuscin isolated from human retinal pigment epithelium cells.

Publication ,  Journal Article
Hong, L; Garguilo, J; Anzaldi, L; Edwards, GS; Nemanich, RJ; Simon, JD
Published in: Photochemistry and photobiology
November 2006

Melanosomes and lipofuscin were isolated from 14-, 59-, and 76-year-old, human retinal pigment epithelium specimens and examined. The morphological features of these samples were studied by scanning electron microscopy and atomic force microscopy, and the photoionization properties were examined by photoelectron emission microscopy. Ovoid- and rod-shaped melanosomes were observed. The size of the granules and the distribution between the two shapes show no significant age-dependent change. However, there is a higher occurrence of irregularly shaped aggregates of small round granules in older samples which suggests degradation or damage to melanosomes occurs with age. The melanosomes from the 14-year-old donor eye are well characterized by a single photoionization threshold, 4.1 eV, while the two older melanosomes exhibit two thresholds around 4.4 and 3.6 eV. Lipofuscin from both young and old cells show two thresholds, 4.4 and 3.4 eV. The similarity of the potentials observed for aged melanosomes and lipofuscin suggest that the lower threshold in the melanosome sample reflects lipofuscin deposited the surface of the melanosome. The amount, however, is not sufficient to alter the density of the melanosome, and therefore these granules do not separate in a sucrose gradient at densities characteristic of the typical melanolipofuscin granule. These data suggest that thin deposits of lipofuscin on the surface of retinal pigment epithelium melanosomes are common in the aged eye and that this renders the melanosomes more pro-oxidant.

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Published In

Photochemistry and photobiology

DOI

EISSN

1751-1097

ISSN

0031-8655

Publication Date

November 2006

Volume

82

Issue

6

Start / End Page

1475 / 1481

Related Subject Headings

  • Spectrophotometry
  • Retina
  • Pigment Epithelium of Eye
  • Middle Aged
  • Microscopy, Electron, Scanning
  • Melanosomes
  • Lipofuscin
  • Light
  • Humans
  • Biophysics
 

Citation

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MLA
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Hong, L., Garguilo, J., Anzaldi, L., Edwards, G. S., Nemanich, R. J., & Simon, J. D. (2006). Age-dependent photoionization thresholds of melanosomes and lipofuscin isolated from human retinal pigment epithelium cells. Photochemistry and Photobiology, 82(6), 1475–1481. https://doi.org/10.1562/2006-03-14-ra-846
Hong, Lian, Jacob Garguilo, Laura Anzaldi, Glenn S. Edwards, Robert J. Nemanich, and John D. Simon. “Age-dependent photoionization thresholds of melanosomes and lipofuscin isolated from human retinal pigment epithelium cells.Photochemistry and Photobiology 82, no. 6 (November 2006): 1475–81. https://doi.org/10.1562/2006-03-14-ra-846.
Hong L, Garguilo J, Anzaldi L, Edwards GS, Nemanich RJ, Simon JD. Age-dependent photoionization thresholds of melanosomes and lipofuscin isolated from human retinal pigment epithelium cells. Photochemistry and photobiology. 2006 Nov;82(6):1475–81.
Hong, Lian, et al. “Age-dependent photoionization thresholds of melanosomes and lipofuscin isolated from human retinal pigment epithelium cells.Photochemistry and Photobiology, vol. 82, no. 6, Nov. 2006, pp. 1475–81. Epmc, doi:10.1562/2006-03-14-ra-846.
Hong L, Garguilo J, Anzaldi L, Edwards GS, Nemanich RJ, Simon JD. Age-dependent photoionization thresholds of melanosomes and lipofuscin isolated from human retinal pigment epithelium cells. Photochemistry and photobiology. 2006 Nov;82(6):1475–1481.
Journal cover image

Published In

Photochemistry and photobiology

DOI

EISSN

1751-1097

ISSN

0031-8655

Publication Date

November 2006

Volume

82

Issue

6

Start / End Page

1475 / 1481

Related Subject Headings

  • Spectrophotometry
  • Retina
  • Pigment Epithelium of Eye
  • Middle Aged
  • Microscopy, Electron, Scanning
  • Melanosomes
  • Lipofuscin
  • Light
  • Humans
  • Biophysics