Revisiting the internal absorption coefficient of the retinal pigment epithelium melanosome

R. D. Glickman, Steven Jacques, R. T. Hall, N. Kumar

Research output: Chapter in Book/Report/Conference proceedingConference contribution

18 Citations (Scopus)

Abstract

Retinal pigment epithelial (RPE) cells of the vertebrate eye contain melanin packaged in structures called melanosomes. Previously, we reported that the bovine melanosome has a laser photodisruption threshold of 153.6 mJ/cm2 at 25 °C and 532 nm (Glickman et al., Proc SPIE 2681:460-467, 1996), and an internal absorption coefficient of 2237 cm-1 (Jacques et al., Proc. SPIE 2681:468-477, 1996). Those values used an estimate of melanosome density inferred from studies of skin laser effects (Jacques et al., J. Invest. Dermatol. 88:88-93, 1987). We now revisit that calculation using a density value obtained from density centrifugation analysis of bovine and baboon RPE melanosomes. Stepped-density gradients (60% to 80%) of the nonionic medium, Nycodenz, were formed, and samples of melanosomes were spun on the gradients in a swinging-bucket rotor at 10,000 rpm for 60 m. Bovine melanosomes formed two populations, one at the interface between 70% and 75%, and the other between 75% and 80%, corresponding to densities of ∼1.38 and ∼1.41 gm/cm3, respectively. Baboon melanosomes migrated to within the same density region. Using a density value of 1.41 gm/cm3, and assuming a water content of 52% for hydrated melanosomes, the internal absorption coefficient was calculated as 2339 cm-1. Although this calculation uses an objective density measurement, the water content remains an estimate, and the actual value in situ may differ.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
EditorsD.D. Duncan, S.L. Jacques, P.C. Johnson
Pages134-141
Number of pages8
Volume4257
DOIs
StatePublished - 2001
Externally publishedYes
EventLaser-Tissue Interaction XII: Photochemical, Photothermal, and Photomechanical - San Jose, CA, United States
Duration: Jan 21 2001Jan 24 2001

Other

OtherLaser-Tissue Interaction XII: Photochemical, Photothermal, and Photomechanical
CountryUnited States
CitySan Jose, CA
Period1/21/011/24/01

Fingerprint

epithelium
pigments
Pigments
Water content
absorptivity
Melanin
Centrifugation
Lasers
baboons
Skin
Rotors
moisture content
melanin
buckets
gradients
vertebrates
estimates
rotors
lasers
thresholds

Keywords

  • Density
  • Laser photodisruption
  • Melanin
  • Nycodenz
  • Optical properties
  • RPE

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

Cite this

Glickman, R. D., Jacques, S., Hall, R. T., & Kumar, N. (2001). Revisiting the internal absorption coefficient of the retinal pigment epithelium melanosome. In D. D. Duncan, S. L. Jacques, & P. C. Johnson (Eds.), Proceedings of SPIE - The International Society for Optical Engineering (Vol. 4257, pp. 134-141) https://doi.org/10.1117/12.434697

Revisiting the internal absorption coefficient of the retinal pigment epithelium melanosome. / Glickman, R. D.; Jacques, Steven; Hall, R. T.; Kumar, N.

Proceedings of SPIE - The International Society for Optical Engineering. ed. / D.D. Duncan; S.L. Jacques; P.C. Johnson. Vol. 4257 2001. p. 134-141.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Glickman, RD, Jacques, S, Hall, RT & Kumar, N 2001, Revisiting the internal absorption coefficient of the retinal pigment epithelium melanosome. in DD Duncan, SL Jacques & PC Johnson (eds), Proceedings of SPIE - The International Society for Optical Engineering. vol. 4257, pp. 134-141, Laser-Tissue Interaction XII: Photochemical, Photothermal, and Photomechanical, San Jose, CA, United States, 1/21/01. https://doi.org/10.1117/12.434697
Glickman RD, Jacques S, Hall RT, Kumar N. Revisiting the internal absorption coefficient of the retinal pigment epithelium melanosome. In Duncan DD, Jacques SL, Johnson PC, editors, Proceedings of SPIE - The International Society for Optical Engineering. Vol. 4257. 2001. p. 134-141 https://doi.org/10.1117/12.434697
Glickman, R. D. ; Jacques, Steven ; Hall, R. T. ; Kumar, N. / Revisiting the internal absorption coefficient of the retinal pigment epithelium melanosome. Proceedings of SPIE - The International Society for Optical Engineering. editor / D.D. Duncan ; S.L. Jacques ; P.C. Johnson. Vol. 4257 2001. pp. 134-141
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