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Biomedical subjects

L Feeney

Publications and source records attributed to L Feeney.

13 recordsLinked to original sources
PubMed1991

Comparison of humerus length with femur length in fetuses with Down syndrome.

A recent report by FitzSimmons et al. demonstrated a greater frequency of upper- versus lower-extremity shortening in autopsies of second-trimester fetuses with trisomy 21. We undertook this study to determine whether this upper-limb shortening could be detected by prenatal ultrasonography in the second trimester and therefore identify fetuses at risk for trisomy 21. A retrospective review of all prenatal sonograms preceding genetic amniocentesis was conducted. Between 1987 and 1990 11 consecutive fetuses between 15 and 22 weeks' gestation with trisomy 21 were identified by genetic amniocentesis. Femur and humerus lengths were plotted on growth curves created from 1470 normal patients between 12 and 26 weeks. Gestational age was confirmed by last menstrual period and biparietal diameter. In fetuses with trisomy 21, seven of 11 humeri were less than 5th percentile, for a sensitivity of 64%, whereas only two of 11 femurs were less than 5th percentile, for a sensitivity of 18%. Biparietal diameter/femur length and biparietal diameter/humerus length ratios were also tested to predict Down syndrome. In only 2 of 11 cases was the biparietal diameter/femur length ratio greater than 95th percentile, whereas the biparietal diameter/humerus length ratio was greater than 95th percentile in 7 of 11. Since all seven were identified by shortened humerus alone, we conclude that humerus length versus gestational age is the simplest and most effective screen. The positive predictive value of an abnormally short humerus length in detecting Down syndrome was 6.8% in our population where the prevalence of Down syndrome was 1 of 173. The present study supports the observations of FitzSimmons et al. that shortened humerus length has a greater sensitivity than femur length in cases of trisomy 21. We conclude that in fetuses at risk for trisomy 21 humerus length should be determined, because it may, if shortened, aid in the prenatal diagnosis.

Anthropometry↗
PubMed1979

Subcellular distribution of free and esterified forms of vitamin A in the pigment epithelium of the retina and in liver.

1. The distribution of vitamin A was examined in various subcellular fractions of rat liver and bovine retinal pigment epithelium. In rat liver, the major portion of the vitamin is in the cytosol, whereas in pigment epithelium, it is concentrated mainly in the microsomes. The microsomal vitamin A of pigment epithelium is tightly bound to membranes, as shown by the inability to release it except by organic solvent extraction or incubation with Triton X-100. 2. In both tissues, two different forms of cytosol vitamin A could be distinguished by ultracentrifugation. The major portion in liver is in the floating lipid phase and consists mainly of retinyl ester. The remainder (less than 10% of the total) is in the underlying infranatant; about 90% of the vitamin A in this fraction is esterified. By contrast, two-thirds of the vitamin A of pigment epithelial cell cytosol is in the infranatant; it consists of both esterified and unesterified retinol. The floating layer in the pigment epithelial cytosol consists entirely of retinyl ester. 3. These two forms of cytosol vitamin A in the pigment epithelium could also be separated by gel filtration on Sephadex G-100 which yielded two distinct fluorescent peaks. The first, which appeared in the void volume and corresponded in all probability to the floating layer obtained by ultracentrifugation, consisted only of retinyl ester. The second peak, which was eluted in approximately the same position as myoglobin, contained only unesterified retinol. It was abolished completely by preincubation with pronase. These findings support the view that the second peak represents the endogenous retinol-retinol binding protein complex of pigment epithelial cytosol. The fluorescent enhancement of the retinol bound to protein in this peak was about 4--5-fold compared to retinol in organic solvents.

Animals↗
PubMed1978

Lipofuscin and melanin of human retinal pigment epithelium. Fluorescence, enzyme cytochemical, and ultrastructural studies.

The life history of melanin and lipofuscin granules of human retinal pigment epithelium (RPE) was studied in 30 human eyes spanning nine decades of life. Autofluorescent granules in the cytoplasm of eye over 30 years of age were shown, ultrastructurally and through lipid solvent extraction, to be lipofuscin granules. Sparse small fluorescent granules in infant eyes were secondary lysosomes containing small droplets of lipid. Flourescent substances in RPE granules of eyes less than 50 years old were more readily extracted with lipid solvents than those in very old eyes (greater than 70). Lipfuscin granules were positive for acid phosphatase and aryl sulfatase activity. Fusions between primary lysosomes and lipofuscin granules were common in older eyes, suggesting that the over-all degradative process involves repeated injection of lysosomal enzymes, i.e., the initial fusion of lysosomes with phagosomes (phagocytized outer segment disks) is only one of several attempts to hydrolyze the membranous material. Some melanin granules showed hydrolytic enzyme reactions. By use of enzyme cytochemistry, fluorescence microscopy, and lipid extraction two types of melanin-containing complex granules were identified: melanin with a cortex of lipofuscin (melanolipofuscin) and melanin with a cortex of nonlipid, enzyme reactive material (melanolysosomes). These findings indicate that melanin commonly becomes incorporated into the lysosomal system of the RPE cell and suggests that it undergoes modification or degradation there. These studies indicate that a dynamic, complex interrelationship exists between the various components of the phagolysosomal system and the melanin granules in the RPE cytoplasm. Also, the observed variation from one human eye to another in the content and lipid extractability of RPE lipofuscin granules suggests that there may be differences in lipid composition of phagocytized photoreceptor disks and/or differences in the degradation of these lipids in the phagolysosomal system of the RPE cell.

Acid Phosphatase↗
PubMed1976

Sulfated glycolipids in ciliary body epithelium.

The sulfated material which locates in the basal membrane of ciliary body epithelium when immature rat eyes are incubated with Na235SO4 was studied. On the basis of its chromatographic behavior compared with standard preparations, we conclude that the material consists of sulfatides.

Animals↗
PubMed1975

Human subretinal fluid. Its cellular and subcellular components.

A light and electron microscopical study of subretinal fluid removed at surgery for rhegmatogenous retinal detachment showed a heterogeneity of cell types originating from the neural retina, pigment epithelium, and wandering cells of the blood. Subcellular organelles sedimenting in the centrifuged pellets could be identified as to cell of origin, health of the parent cell, and time since cell rupture. Acellular specimens were typical of angiomatous detachments or long-standing rhegmatogenous detachments. Because various mechanisms of cellular pathophysiology contribute to the destructive and reparative processes during retina detachment, the cytologic analysis of subretinal fluid becomes a useful tool in understanding the biological processes that affect visual recovery or impairment after successful retinal detachment surgery.

Biopsy, Needle↗
PubMed1975

Hereditary cataracts in deer mice (Peromyscus maniculatus).

A new type of hereditary cataract was predicted in the deer mouse (Peromyscus maniculatus) by the presence of syndactyly of the hind feet. Early morphologic changes were found in the equatorial cells that differentiated into new lens fibers. Later swelling at the anterior and posterior poles of these cells produced lens opacities. Anterior and posterior subcapsular cataracts progressed to a hypermature shrunken lens.

Animals↗
PubMed1975

Sulfate and galactose metabolism in differentiating ciliary body and iris epithelia: autoradiographic and ultrastructural studies.

Immature and adult rat eyes were bisected and incubated with 35-SO4 and 3-U-galactose in short-term pulse-chase experiments. Autoradiographs (ARG) of the tissue revealed that very little sulfate is incorporated by the peripheral neural retina, the pigment epithelia of the retina, ciliary body, or iris. The inner, inverted optic cup cells at the ora serrata, i.e., those that are undergoing differentiation into the unpigmented epithelium of the ciliary body, incorporate large amounts of 35-sulfate into "fixable" macromolecules. The sulfate label is chased from the apically located Golgi apparatus to the basal surface of these cells within one hour. Ultrastructurally, these cells are beginning to develop lateral and basal invaginations of the plasma membrane characteristic of the adult secretory epithelial cells. Electron microscopic ARG show label associated with the plasma membranes. The sulfated macro-molecules at this site appear to be glycolipids and glycoproteins rather than glycosaminoglycans. The preferential synthesis of these macromolecules and their placement at the cellular site of aqueous humor production suggests a role for these sulfated substances in establishing, and perhaps maintaining, that secretory process. 3-H-galactose was incorporated into "fixable" macromolecules to some degree by all the neuroepithelial cells. After chase incubation, ARG showed a high concentration of label in differentiated retinal pigment epithelium (RPE), but not in undiffenentiated peripheral RPE. Ciliary body unpigmented and pigment epithelium, and iris muscle cells incorporate galactose, but to a lesser degree than either RPE or corneal endothelial cells.

Age Factors↗