Retinal pigment

So far we have exclusively discussed time-resolved absorption spectroscopy with visible femtosecond pulses. It has become recently feasible to perfomi time-resolved spectroscopy with femtosecond IR pulses. Flochstrasser and co-workers [M, 150. 151. 152. 153. 154. 155. 156 and 157] have worked out methods to employ IR pulses to monitor chemical reactions following electronic excitation by visible pump pulses these methods were applied in work on the light-initiated charge-transfer reactions that occur in the photosynthetic reaction centre [156. 157] and on the excited-state isomerization of tlie retinal pigment in bacteriorhodopsin [155]. Walker and co-workers [158] have recently used femtosecond IR spectroscopy to study vibrational dynamics associated with intramolecular charge transfer these studies are complementary to those perfomied by Barbara and co-workers [159. 160], in which ground-state RISRS wavepackets were monitored using a dynamic-absorption technique with visible pulses. 

Disorder characterized by atrophy ofthe choroid (the thin membrane covering most of the posterior of the eye between the retina and sclera) and degeneration of the retinal pigment epithelium resulting in night blindness. The disease is caused by mutations in Rab escort protein Repl (component A of Rab geranylgeranyl transferase). 

LUTTY G, GRUNWALD J, MAjji A B, UYAMA M and YONEYA s (1999) Changes in choriocapillaris and retinal pigment epithelium (RPE) in age-related macular degeneration. Mol Vis. 5 35-8. 

Melanins are prodnced in mammals in two types of cells of different developmental origin (1) the melanocytes of the skin, hair, choroids and iris and (2) the retinal pigment epithelium (RPE). Specialized organelles of the melanocytes, the melano-somes, synthesize and store eumelanins and phaeomelanins. 

Seagle, B.L. et al., Melanin photoprotection in the human retinal pigment epithelium and its correlation with light-induced cell apoptosis, Proc. Natl. Acad. Sci. USA, 102, 8978, 2005. 

Wang, Z., Dillon, J., and Gaillard, E. R., Antioxidant properties of melanin in retinal pigment epithelial cells, Photochem. PhotobioL, 82, 474, 2006. 

The retina comprises two principal components, the non-neural retinal pigment epithelium and the neural retina. The retinal pigment epithelium is an essential component of the visual system both structurally and functionally. It is important for the turnover and phagocytosis of photoreceptor outer segments, the metabolism of retinoids, the exchange of nutrients between the photoreceptors, and the choroidal blood vessels and the maintenance of an efficient outer blood-retinal barrier. 

Figure 7. Expression pattern of the mouse tyrosinase gene during embryonic development and its recapitulation in transgenic mice as determined by in situ hybridization (Beermann et al., 1992a). Black box, mouse tyrosinase open box, transgene ptrTyrf striped box, ptrTyr5. Interrupted boxes indicate variations between lines. RPE, retinal pigment epithelium e, days of gestation d0.5, newborn.

Parish, C. A. et al. (1998). Isolation and one-step preparation of A2E and iso-A2E, fluorophores from human retinal pigment epithelium. Proceedings of the National Academy of Sciences 95 2988-2995. 

Lutein and zeaxanthin are the dominant carotenoids in nonretinal eye tissue, and lycopene and p-carotene have been found in the ciliary body, which after the retina and the retinal pigment epithelium (RPE) contains the highest quantity of carotenoids (Bernstein et al. 2001). The orbital adipose tissue also contains measurable quantities of lutein and p-carotene, and possibly other carotenoids as minor constituents (Sires et al. 2001). It is also interesting to note that lutein was recently identified in the vitreous body of human fetuses, 15-28 weeks old (Yakovleva et al. 2007). However, these results may have to be considered with caution, because the vitreous bodies were described as substantially being penetrated with hyaloid blood vessels, which could have contaminated the vitreous with blood. 

Leung, I. Y., M. M. Sandstrom et al. (2004). Nutritional manipulation of primate retinas, II Effects of age, n-3 fatty acids, lutein, and zeaxanthin on retinal pigment epithelium. Invest. Ophthalmol. Vis. Sci. 45(9) 3244-3256. 

Numerous studies have demonstrated that degradation products of (3-carotene exhibit deleterious effects in cellular systems (Alija et al., 2004, 2006 Hurst et al., 2005 Salerno et al., 2005 Siems et al., 2003). A mixture of (3-carotene degradation products exerts pro-apoptotic effects and cytotoxicity to human neutrophils (Salerno et al., 2005 Siems et al., 2003), and enhances the geno-toxic effects of oxidative stress in primary rat hepatocytes (Alija et al., 2004, 2006), as well as dramatically reduces mitochondrial activity in a human leukaemic cell line, K562, and RPE 28 SV4 cell line derived from stably transformed fetal human retinal pigmented epithelial cells (Hurst et al., 2005). As a result of degradation or enzymatic cleavage of (3-carotene, retinoids are formed, which are powerful modulators of cell proliferation, differentiation, and apoptosis (Blomhoff and Blomhoff, 2006). 

Ahir, A, Guo, L, Hussain, AA, and Marshall, J, 2002. Expression of metalloproteinases from human retinal pigment epithelial cells and their effects on the hydraulic conductivity of Bruch s membrane. Invest Ophthalmol Vis Sci 43, 458-465. 

Anderson, DH, Ozaki, S, Nealon, M, Neitz, J, Mullins, RF, Hageman, GS, and Johnson, LV, 2001. Local cellular sources of apolipoprotein E in the human retina and retinal pigmented epithelium implications for the process of drusen formation. Am J Ophthalmol 131, 767-781. 

Aukunuru, JV, Sunkara, G, Bandi, N, Thoreson, WB, and Kompella, UB, 2001. Expression of multidrug resistance-associated protein (MRP) in human retinal pigment epithelial cells and its interaction with BAPSG, a novel aldose reductase inhibitor. Pharm Res 18, 565-572. 

Bailey, KR, Ishida, BY, Duncan, KG, Kane, JP, and Schwartz, DM, 2004. Basal reverse cholesterol transport of retinal pigment epithelium cell digested photoreceptor outer segment lipids. Invest Ophthalmol Vis Sci 45, U721. 

Chen, M, Forrester, JV, and Xu, H, 2007. Synthesis of complement factor H by retinal pigment epithelial cells is down-regulated by oxidized photoreceptor outer segments. Exp Eye Res 84, 635-645. 

Chichili, GR, Nohr, D, Schaffer, M, von Lintig, J, and Biesalski, HK, 2005. Beta-carotene conversion into vitamin A in human retinal pigment epithelial cells. Invest Ophthalmol Vis Sci 46, 3562-3569. 

Constable, PA, Lawrenson, JG, Dolman, DE, Arden, GB, and Abbott, NJ, 2006. P-Glycoprotein expression in human retinal pigment epithelium cell lines. Exp Eye Res 83, 24—30. 

Crane, U, Wallace, CA, McKillop-Smith, S, and Forrester, JV, 2000b. CXCR4 receptor expression on human retinal pigment epithelial cells from the blood-retina barrier leads to chemokine secretion and migration in response to stromal cell-derived factor 1 alpha. J Immunol 165,4372-4378. 

Cui, HS, Hayasaka, S, Zhang, XY, Hayasaka, Y, Chi, ZL, and Zheng, LS, 2006. Effect of berberine on interleukin 8 and monocyte chemotactic protein 1 expression in a human retinal pigment epithelial cell line. Ophthalmic Res 38, 149-157. 

Dunn, KC, Aotaki-Keen, AE, Putkey, FR, and Hjelmeland, LM, 1996. ARPE-19, a human retinal pigment epithelial cell line with differentiated properties. Exp Eye Res 62, 155-169. 

Ebihara, N, Chen, L, Tokura, T, Ushio, H, Iwatsu, M, and Murakami, A, 2007. Distinct functions between toll-like receptors 3 and 9 in retinal pigment epithelial cells. Ophthalmic Res 39, 155-163. 

Elner, VM, 2002. Retinal pigment epithelial acid lipase activity and lipoprotein receptors Effects of dietary omega-3 fatty acids. Trans Am Ophthalmol Soc 100, 301-338. 

Ershov, AV and Bazan, NG, 2000. Photoreceptor phagocytosis selectively activates PPARgamma expression in retinal pigment epithehal cells. J Neurosci Res 60, 328-337. 

Hahn, P, Milam, AH, and Dunaief, JL, 2003. Maculas affected by age-related macular degeneration contain increased chelatable iron in the retinal pigment epithelium and Bruch s membrane. Arch Ophthalmol 121, 1099-1105. 

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