X-ray Microanalysis of Ocular Melanin in Pigs Maintained on Normal and Low Zinc Diets

Samuelson, Don; Smith, Patricia M.; Ulshafer, Robert J.; Hendricks, Deloy G.; Whitley, R. David; Hendricks, H. B.; Leone, N. C.

doi:10.1006/exer.1993.1009

Cited by 44 publications

(37 citation statements)

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“…Specimens were examined by using the SEM freeze-dried technique (35). Tissue samples that included retina͞choroid͞sclera were obtained as 5-mm buttons, centered 3.5 mm from the end of the pecten at the central posterior region of the eyecup to ensure consistent localization for morphological analyses.…”

Section: Methodsmentioning

confidence: 99%

Ionic control of ocular growth and refractive change

Liang

Junghans

Crewther

2006

Proc. Natl. Acad. Sci. U.S.A.

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The physiological mechanisms underlying the abnormal vitreal and ocular growth and myopic refractive errors induced under conditions of visual form deprivation in many animal species, including humans, are unknown. This study demonstrates, using energy dispersive x-ray microanalysis, a systematic pattern of changes in the elemental distribution of K, Na, and Cl across the entire retina in experimental form deprivation myopia and in the 5 days required for refractive normalization after occluder removal. In our report we link the ionic environment associated with physiological activity of the retina under a translucent occluder to refractive change and describe large but reversible environmentally driven increases in potassium, sodium, and chloride abundances in the neural retina. Our results are consistent with the notion of ionically driven fluid movements as the vector underlying the myopic increase in ocular size. New treatments for myopia, which currently affects nearly half of the human population, may result.form deprivation myopia ͉ retinal pigment epithelium ͉ x-ray microanalysis

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Section: Methodsmentioning

confidence: 99%

Ionic control of ocular growth and refractive change

Liang

Junghans

Crewther

2006

Proc. Natl. Acad. Sci. U.S.A.

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“…Immature cells might have the least zinc in their melanin granules in 14-day-old normal littermates, and the abnormal distribution of zinc might be similar to that of copper in hemizygote macular mice (Tsurui and Sugie, 1990). Samuelson et al (1993) reported that the levels of zinc, calcium and iron in RPE melanosomes in aged pigs fed low zinc diets were consistently lower than in control animals, while the level of copper was higher than in control animals. In the present study, we found that calcium and copper decreased and zinc increased significantly with age in melanin granules in the RPE and choroid of hemizygote macular mice.…”

Section: Results Of Unpaired T-test ( P 0n05) In Specific X-ray Countmentioning

confidence: 93%

“…Our freeze-embedding methods (Takano et al, 1994) are able to keep the morphology of the retina, to reduce the loss of the several elements, to make an ultrathin section more easily, to observe clearly and to keep the sample for a long time, because the tissues are fixed quickly, frozen and embedded in Lowicryl K4M. Samuelson et al (1993) reported that there was little difference in X-ray microanalysis between glutaraldehyde fixed tissues and cryofixed specimens. Although we think that the rapid freezing method or the freeze-drying method is better in general than the freeze-embedding method for X-ray microanalysis and F.…”

Section: Discussionmentioning

confidence: 98%

X-ray Microanalysis of Melanin Granules of Retinal Pigment Epithelium and Choroid in Hereditary Copper Deficient Mice (Macular Mice)

Mishima

Amemiya

Takano

1999

Experimental Eye Research

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“…It is associated with the melanin of pigmented tissues [37]. Samuelson et al showed changes in the elemental content of RPE and choroidal melanosomes of pigs fed a low-zinc diet [42], with a significant decrease of zinc concentration. Cytotoxicity of zinc, especially exceeding 10 −4 mol/l, is also reported [5], since zinc was shown to inhibit the anchorage-dependent growth of Cloudman S91 melanoma [4].…”

Section: Discussionmentioning

confidence: 98%