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Biomedical subjects

L Feeney-Burns

Publications and source records attributed to L Feeney-Burns.

28 records · Page 2Linked to original sources
PubMed1981

Maculopathy in cynomolgus monkeys. A correlated fluorescein angiographic and ultrastructural study.

Maculae of seven cynomolgus macaque monkeys (Macaca fascicularis) showing abnormalities in color fundus photographs and fluorescein angiograms were studied in serial sections by light and electron microscopy and compared with three eyes without clinically visible defects in the macula. Maculae that showed hyperfluorescent nonleaking window defects showed no drusen or interruptions in the retinal pigment epithelium (RPE). Six of these monkeys had mis-shapen foveal depressions, all showed some degree of photoreceptor degeneration, and one had cells in Bruch's membrane. Bright yellow spots correlated with scattered RPE filled with lipid vacuoles. Shallow RPE elevations correlated with diffuse nonleaking window defects. Patches of RPE deficient in melanin occurred at sites of hyperfluorescence. Quantitative studies showed that maculae with window defects had more lipofuscin and less melanin per RPE cell. Maculae deemed normal by photography showed degenerating photoreceptors.

Animals↗
PubMed1980

Enzymatic esterification of vitamin A in the pigment epithelium of bovine retina.

The kinetic properties and subcellular distribution of an esterifying enzyme in the pigment epithelium of bovine retina have been studied using both [1-3H]retinol and [3H]retinol bound to cellular retinol-binding protein as substrates. The most active esterifying fraction in pigment epithelial cell preparations was the microsomes, but the lysosome plus mitochondria fraction also showed some activity, probably due to endoplasmic reticulum present as an impurity. The microsomal enzyme showed optimum activity at pH 7.5, and the reaction was linear up to 30 microgram protein and for the first 10-15 min. The apparent Km values were 16.6 . 10(-6) and 5.5 . 10(-6) M for [3H]retinol and bound [3H]retinol, respectively. This is the first time that retinol bound to cellular retinol-binding protein has been shown to undergo metabolic transformation. The microsomal esterifying activity was destroyed by boiling for 1 min, or after freezing for 2 months. No clear requirement for ATP, CoA or fatty acid could be demonstrated. Of all the other tissues examined under the same experimental conditions as those used for the pigment epithelium, only intestine showed measurable activity. With larger amounts of tissue protein and longer incubation periods, activity was also detectable in microsomes of liver, testis and retina.

Animals↗
PubMed1980

Lipofuscin of human retinal pigment epithelium.

Analysis of the fluorescent spectra of chloroform-methanol extracts of human retinal pigment epithelium confirmed the presence of lipofuscin pigments in the pigment epithelium of older individuals. Similar fractions in the pigment epithelium of young individuals were present in insufficient quantities for spectral analysis. Electron microscopy of the pigment epithelium of these eyes showed few or no lipofuscin granules in young eyes but large numbers in older eyes.

Adult↗
PubMed1980

Cataract-webbed trait in Peromyscus. II. Biomicroscopy and histology of eyes.

A longitudinal biomicroscopic study of lenses and fundi of over 2,000 Peromyscus maniculatus (deer mice) which have cataracts as an autosomal recessive trait has been correlated with histologic development of cataracts. By selective breeding, early-onset cataracts (Type I), which are frequently associated with abnormal closure of the fetal fissure and hyaloid vascular abnormalities, have been separated from later-onset (Type II) cataracts, which are more heterogeneous. Type I cataracts occur in syndactylous deer mice, develop rapidly, and histologically may show backward migration of disrupted lens bow cells before lens opacity is apparent biomicroscopically. Posterior subcapsular cataracts then develop and spread centrally and inferonasally to the equatorial area and then to the entire equator. The nucleus opacifies in either a "shell" pattern or as isolated dots. Anterior cortical opacification progresses to mature cataract. Histologically, abnormal migration and proliferation of lens epithelium and enlargement and vacuolar degeneration of the basal (posterior) process of cortical lens fibers are early changes in Type I cataracts. Disruption of the lens bow with failure of differentiation and inward turning of lens epithelium to become lens fibers occurs concurrently. Type II cataracts may follow the developmental pattern of Type I but are rarely associated with severe hyaloid vascular abnormalities and progress more slowly. About 6% of animals develop diabetes, which is not associated with the cataract-webbed trait.

Animals↗
PubMed1980

Ultrastructure and acid phosphatase activity in hereditary cataracts of deer mice.

Lenses of cataract-webbed (cw) Peromyscus maniculatus were examined by electron microscopy and compared to age-matched normal deer mouse lenses. Precataractous lenses of offspring of cw/cw matings were examined and compared to early cataract development in the opposite eye of the same animal. The earliest ultrastructural change leading to disturbance of lens transparency was cell fusion and formation of fiber cell syncytia in the posterior subcapsular region. Fiber cells lost their regular hexagonal packing. Small osmiophilic densities on the plasma membrane coincided with many of the sites of cell confluency. Larger osmiophilic whorls were usually localized in ball-and-socket interlocking junctions after the opacity spread. Epithelial cells from the nasal ventral equator migrated to the posterior pole. Later when underlying cortical fibers ruptured, the migrated cells phagocytized lens proteins and incorporated them in acid-phosphatase positive lysosomes. Fiber cells 3 to 20 layers deep in the cortex of normal and cataractous lenses had acid phosphatase reaction product coating the plasma membrane; the possible significance of this finding is discussed. We postulate that this hereditary cataract results from a defect in turnover and control of plasma membrane components.

Acid Phosphatase↗
PubMed1980

Diet-related macular anomalies in monkeys.

Fundus color photographs and retinal fluorescein angiograms were obtained from 48 nonhuman primates of three macaque species. Yellow pigmentation of the macula was present in monkeys fed a standard laboratory diet containing xanthophylls but was absent in animals maintained on semipurified or liquid formula diets with no xanthophyll content. Plasma levels of xanthophylls ranged from 0.5 to 2.4 microliters/ml in monkeys receiving the standard diet but were undetectable in animals raised on semipurified or liquid formula diets. Fluorescein angiograms revealed foveal areas of hyperfluorescence in almost all monkeys; however, the degree of hyperfluorescence was significantly greater in monkeys maintained on the semipurified or liquid formula diets.

Animals↗