Reduced and total ascorbate in guinea pig eye tissues in response to dietary intake

Berger, Joseph J.; Shephard, D.P.E. Roy J.; Morrow, Frank D.; Sadowski, James A.; Haire, Teresa; Taylor, Allen

doi:10.3109/02713688809033197

Cited by 35 publications

(12 citation statements)

References 16 publications

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“…These data are con sistent with prior experiments in which rela tionships were established between dietary content and eye tissue levels of ascorbate in haired Hartley guinea pigs [11,12]. For ani mals fed diets rich in ascorbate, most of the ascorbate was found in the reduced form, and, within the eye, the intertissue differences were markedly diminished.…”

Section: Tissue Ascorbate Levelssupporting

confidence: 74%

“…For ani mals fed diets rich in ascorbate, most of the ascorbate was found in the reduced form, and, within the eye, the intertissue differences were markedly diminished. This was also noted in haired Hartley animals [11].…”

Section: Tissue Ascorbate Levelsmentioning

confidence: 65%

“…The Low-C diet (~ 5 mg/day) provided di etary levels of ascorbate, which were adequate to prevent scurvy, while the High-C diet (74 mg/day) provided more than ten times the daily recommended requirement for guinea pigs [ 19], This is enough to saturate all tissues in the parental strain with ascorbate [11,12], Ascorbate levels were evaluated at the conclu sion of the experiment to determine the bio availability of ascorbate in organs of interest. Table 1 shows that the diets resulted in two groups of hairless animals with different as corbate status.…”

Section: Tissue Ascorbate Levelsmentioning

confidence: 99%

“…Plasma specimens were combined with an equal volume of PCA, vortexed, and centrifuged as described previously. Supernatant frac tions from all specimen types were analyzed in dupli cate for reduced and total ascorbate as noted pre viously [11,17], Control experiments were performed to determine whether certain compounds interfere with the assay for total ascorbate. Assays included glucose (1 or 7 mg/ ml), sucrose (10 mg/ml), and a-ketogulonic acid (20 pg/ml), each alone and in combination with 10 pg/ ml ascorbate.…”

Section: Ascorbate Analysismentioning

confidence: 99%

“…This also presented an opportunity to use guinea pigs as a model for cataract. With cataractous guinea pigs, it would be possible to test relationships between ascorbate and cata ract, since (1) guinea pigs are one of the few laboratory animals that, like humans, require ascorbate, and (2) ascorbate levels in guinea pig tissues (including eye) can be regulated by dietary intervention [11,12], Furthermore, these relationships are of interest, since pre liminary data indicate that enhanced dietary ascorbate is associated with diminished cata ractlike damage in guinea pigs [6], with de layed cataract in selenite-stressed mice [13], and with diminished cataract risk in humans [14,15]. Thus, the acetone cataract model appeared a very attractive tool.…”

Section: Introductionmentioning

confidence: 99%

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Relationships between Acetone, Cataracts, and Ascorbate in Hairless Guinea Pigs

Taylor¹,

Smith²,

Palmer³

et al. 1993

Ophthalmic Res

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Acetone is one of the most commonly used industrial solvents. Recent literature indicated that in guinea pigs, but not rabbits, acetone is cataractogenic and that elevated acetone exposure is also associated with depressed aqueous ascorbate levels. Other work indicated that aqueous and lens levels of ascorbate are closely linked and that depressed ascorbate status is related to cataract. Taken together, these papers suggested that acetone exposure, depressed ascorbate levels, and cataract are related, possibly causally. While the possibility that acetone is cataractogenic presented a major health concern, it also presented an opportunity to develop a new model of cataract in which hypotheses regarding anticataractogenic effects of ascorbate could be tested. Albino hairless guinea pigs are immunocompetent animals derived from albino Hartley guinea pigs. Animals were fed diets containing low (4.9 mg/day) and high (55 mg/day) levels of ascorbate. This resulted in distinct groups of animals, one with high tissue ascorbate levels and the other with low, but nonscorbutic ascorbate levels. The tissue levels of ascorbate and the relationship between tissue ascorbate levels and dietary intake indicate that with respect to ascorbate uptake, transport, and concentration, these animals are identical to the standard albino Hartley animals. Daily exposure to acetone was extended for 6 months, with a total applied dose of 65 ml. Absorption of the solvent was maximized by the use of hairless animals. Despite exposure of the animals to higher levels of acetone, in no case (n = 20) were cataracts observed over a 2-year period. This is consistent with results using rabbits. The data show that the hairless guinea pig is a fine model for studies in which ascorbate bioavailability is of importance. However, other models to test the cataractogenic potential of acetone and anticataract effects of ascorbate are needed.

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Section: Tissue Ascorbate Levelssupporting

confidence: 74%

Section: Tissue Ascorbate Levelsmentioning

confidence: 65%

Section: Tissue Ascorbate Levelsmentioning

confidence: 99%

Section: Ascorbate Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Relationships between Acetone, Cataracts, and Ascorbate in Hairless Guinea Pigs

Taylor¹,

Smith²,

Palmer³

et al. 1993

Ophthalmic Res

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Vitreous humor and albumin augment the proliferation of cultured retinal precursor cells

Yang

Klassen

Pries

et al. 2008

J of Neuroscience Research

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Intravitreal injection is an important delivery route for studies involving the transplantation of various types of precursor cells to the retina; however, the effect on these cells of exposure to the vitreous microenvironment has not been specifically investigated. Here vitreous humor was evaluated for the potential to influence the proliferation of rat retinal precursor cells in vitro. Cells were isolated at embryonic day 19 and plated in standard proliferation medium in the presence or absence of fluid expressed from porcine vitreous humor. Cellular proliferation at different concentrations of vitreous fluid supplementation was quantified by using a (3)H-thymidine incorporation assay. Active components of vitreous fluid were partially characterized by gel filtration chromatography (GFC) and UV spectral analysis. The effect of each vitreous fraction on proliferation was determined as well. Results showed that addition of 20% vitreous fluid to primary rat retinal cultures significantly increased (3)H-thymidine incorporation compared with growth medium without vitreous supplementation. A vitreous fraction showing growth-promoting activity was localized to a molecular mass range <1000 Da, consistent with ascorbic acid. Ascorbic acid was confirmed in vitreous fluid by UV spectral analysis. Growth-augmenting activity was present in higher molecular mass vitreous fractions, consistent with protein components. Albumin, the major protein in vitreous fluid, was found to augment proliferation. Because vitreous-associated augmentation of retinal precursor proliferation remains an epidermal growth factor-dependent phenomenon, the proliferative status of transplanted cells in the vitreous cavity is likely determined by a combination of factors.

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Protein Oxidation and Proteolytic Degradation General Aspects and Relationship to Cataract Formation

Davies

1990

Advances in Experimental Medicine and Biology

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Reduced and total ascorbate in guinea pig eye tissues in response to dietary intake

Cited by 35 publications

References 16 publications

Relationships between Acetone, Cataracts, and Ascorbate in Hairless Guinea Pigs

Relationships between Acetone, Cataracts, and Ascorbate in Hairless Guinea Pigs

Vitreous humor and albumin augment the proliferation of cultured retinal precursor cells

Protein Oxidation and Proteolytic Degradation General Aspects and Relationship to Cataract Formation

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