Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has been hypothesized that there are differences between membrane-associated glycoconjugates of wounded (migrating) epithelium and those of nonwounded (stationary) epithelium. To test this hypothesis, wheat germ agglutinin-ferritin (WGA-Fe) and concanaval in A-ferritin (Con A-Fe) binding to apical membranes of wounded and nonwounded rabbit corneal epithelia were compared. Epithelial abrasions of the superior half of the cornea were allowed to heal in vivo for six hours. Fixed corneas were then incubated with lectin-ferritin and prepared for electron microscopy. Measurements (ferritin particles per linear um of membrane) of WGA-Fe indicated that binding to leading cells (40.7 particles/um), to areas 20 to 35 cells behind the leading edge (46.5 particles/um) and to nonwounded epithelium (45.1 particles/um) from contralateral eyes were not significantly different. A competitive inhibitor of WGA, 0.2M N-acetylglucosamine, however, blocked 94 percent of WGA binding on leading cells (2.3 particles/um), while binding persisted in areas behind the leading edge (39.5 particles/um) and on nonwounded epithelium (43.6 particles/um). This indicates that leading cell surfaces have a weak affinity for WGA. Unlike WGA, Con A showed a distinct preference for leading-edge cells (33.9 particles/um) compared to nonwounded epithelium (9 particles/um). In areas 20-35 cells behind the leading edge, Con A binding was intermediate to these two extremes.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Wheat germ agglutinin and concanavalin A binding during epithelial wound healing in the cornea. 309 51

Monoclonal antibodies, specific against cell surface differentiation antigens of human corneal epithelial cells, were developed using epithelial cells resected from human corneas as the immunogens. One of these antibodies reacted specifically with corneal epithelial cells and not with epithelial cells of other tissues when tested by an indirect immunoperoxidase technique. Nonidet P-40 extracts of different subcellular fractions of human corneal epithelial cells were tested for their reactivity against this antibody using an enzyme-linked immunosorbent assay. The results indicated that the antigen recognized by this antibody is associated with the plasma membrane. This was further verified by immuno-electron-microscopic analysis using ferritin-conjugated anti-mouse IgG antibody. This antigen was not detectable in the corneal epithelial cells in primary cultures nor in the epithelial cells from early stages of developing cornea (12 to 18 weeks in utero) but was present in the epithelial cells in the corneas of an 8-month-old infant. Therefore, this surface-associated antigen identified in the present study is a developmentally regulated marker of human corneal epithelium.
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PMID:Corneal epithelial-specific cell surface antigen recognized by a monoclonal antibody. 376 Jul 53

Scanning electron microscopy (SEM) of mouse cornea and conjunctiva fixed with picric acid-paraformaldehyde-glutaraldehyde (PA-P-G) mixture revealed a thin layer of amorphous material covering the microvilli of the corneal surface cells. At the transmission electron microscopic (TEM) level, this layer of material stained positively with dialyzed iron, alcian blue and cationized ferritin, all of which are markers for anionic sulfate or carboxyl groups. The corneal surface was negative for high iron diamine, which specifically stains sulfate groups. These results indicate that the murine ocular surface is rich in carboxyl groups. Treatment with neuraminidase prior to fixation significantly reduced (P less than 0.005) cationic ferritin binding, suggesting that most of the carboxyl groups at the ocular surface are associated with sialic acid residues. The corneal surface also stained positively at the TEM level when a periodic acid-thiocarbohydrazide-silver protein sequence (PA-T-SP) was applied. This result indicated the presence of periodic acid-Schiff (PAS)-positive glycoprotein and glycolipid at the ocular surface.
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PMID:Complex carbohydrates at the ocular surface of the mouse: an ultrastructural and cytochemical analysis. 620 40

Twenty-three of 55 patients who underwent refractive keratoplasty for the correction of aphakia were found to have a pigmented corneal epithelial line similar to the Fleischer ring. In 21 of 23 cases, the pigmented ring was adjacent to the superficial keratectomy scar that resulted from the keratorefractive operation. In two cases, the pigmented line was located central to the lamellar keratectomy scar. Histopathologic study demonstrated that the line was due to iron in the form of ferritin particles deposited within basal corneal epithelial cells. We believe that the steep anterior corneal curvature (average, 51.45 diopters) and changes in corneal topography at or central to the margin of the lamellar keratoplasty may lead to malapposition of the eyelid to the cornea and cause disturbances in the precorneal tear film. Iron from the tears may then be deposited in the corneal epithelium in areas of tear pooling.
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PMID:Corneal iron lines after refractive keratoplasty. 636 Jan 9

Plus/minus screening of the rabbit corneal cDNA library was performed using corneal and iris RNA as probes. Thirteen clones were isolated: three ferritin H-chains, a NADH-ubiquinone oxidoreductase B22 subunit, an alpha 1 type VIII collagen, a 25 KDa FKBP-506 binding protein (FKBP25), a thrombospondin 2, and six unknown clones. Although proteins translocated from these isolated mRNA are not corneal specific, they play an important role in the cornea. None of the isolated known mRNAs maps to chromosome 1, 16, or 20. These clones, thrombospondin excepted, were not observed in the high frequency clones in the profile of the aortic endothelial cDNA library.
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PMID:Plus/minus screening of rabbit corneal endothelial cDNA library. 950 3

The fine structure of collagen fibrils at sites of antigen-antibody interaction is described. Following injection of antigen (BSA or ferritin) into the center of the cornea of hyperimmune rabbits, an acidophilic ring of precipitate forms at the periphery of the cornea, where antigen and antibody interact in optimal proportions. The precipitate is soon removed by infiltrating polymorphs, but persists longer in leukopenic animals. Electron microscopic examination of the cornea showed no alteration of the collagen fibrils in the area of antigen-antibody precipitation or in the remaining cornea. Contrary to many claims there was no swelling, fragmentation, or disintegration of the fibrils and they had a normal periodicity. Polymorphs infiltrated the precipitates and phagocytosed the antigen-antibody complexes. There was some ultrastructural evidence that degradation of the complexes took place in the polymorphs.
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PMID:ALLERGIC INFLAMMATION. III. THE FINE STRUCTURE OF COLLAGEN FIBRILS AT SITES OF ANTIGEN-ANTIBODY INTERACTION IN ARTHUS-TYPE LESIONS. 1406 5

Physiological studies have demonstrated that ions, as well as large molecules such as hemoglobin or fluorescein, can diffuse across and within the cornea. Most of the substrates for corneal metabolism are obtained from aqueous humor filling the anterior chamber. In order to receive its nutrients and in order to maintain its normal conditions of hydration, the avascular cornea must transport relatively large amounts of solute and solvent across the cellular layers which cover this structure. It has been suggested in the past that there may be a morphological basis for the transport of large amounts of solvents and solutes by cells by the mechanism of pinocytosis. The use of electron-opaque markers to study fluid movements at the electron microscope magnification level was described by Wissig (29). The present study describes the fine structure of the normal rabbit cornea and the pathways of transport of colloidal particles by the cornea in vivo. Rabbit corneas were exposed in vivo to suspensions of saccharated iron oxide, thorium dioxide, or ferritin by injection of the material into the anterior chamber. In other experiments thorium dioxide or saccharated iron oxide was injected into the corneal stroma, producing a small bleb. Particles presented at the aqueous humor surface of the rabbit corneal endothelium are first attached to the cell surface and then pinocytosed. It appears that the particles are carried around the terminal bar by an intracellular pathway involving the pinocytosis of the particles and their subsequent transport in vesicles to the lateral cell margin basal to the terminal bar. Particles introduced at the basal surface of the endothelium (via blebs in the corneal stroma) are apparently carried through the endothelial cells in membrane-bounded vesicles without appearing in the intercellular space. There appears to be free diffusion of these particles through Descemet's membrane and the corneal stroma. The stromal cells take up large quantities of the particles when blebs are injected into the stroma.
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PMID:Studies on the cornea. I. The fine structure of the rabbit cornea and the uptake and transport of colloidal particles by the cornea in vivo. 1445 75

We have a developed a novel and practical method of imaging the cornea under ultraviolet (UV) light using a digital medium. Wavelengths of 336-371 nm were used to illuminate the cornea. Images were recorded using a UV Nikkor lens and a digital charged coupled device (CCD). Images obtained showed ferritin lines not visible under white light. This study concluded that 336-371 nm is comparable to shorter wavelengths for the imaging of ferritin in the cornea and that a digital image capture system was comparable to that of film.
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PMID:Digital imaging of the human cornea in vivo with ultraviolet light. 1684 26

Iron is essential for many metabolic processes but can also cause damage. As a potent generator of hydroxyl radical, the most reactive of the free radicals, iron can cause considerable oxidative stress. Since iron is absorbed through diet but not excreted except through menstruation, total body iron levels buildup with age. Macular iron levels increase with age, in both men and women. This iron has the potential to contribute to retinal degeneration. Here we present an overview of the evidence suggesting that iron may contribute to retinal degenerations. Intraocular iron foreign bodies cause retinal degeneration. Retinal iron buildup resulting from hereditary iron homeostasis disorders aceruloplasminemia, Friedreich's ataxia, and panthothenate kinase-associated neurodegeneration cause retinal degeneration. Mice with targeted mutation of the iron exporter ceruloplasmin have age-dependent retinal iron overload and a resulting retinal degeneration with features of age-related macular degeneration (AMD). Post mortem retinas from patients with AMD have more iron and the iron carrier transferrin than age-matched controls. Over the past 10 years much has been learned about the intricate network of proteins involved in iron handling. Many of these, including transferrin, transferrin receptor, divalent metal transporter-1, ferritin, ferroportin, ceruloplasmin, hephaestin, iron-regulatory protein, and histocompatibility leukocyte antigen class I-like protein involved in iron homeostasis (HFE) have been found in the retina. Some of these proteins have been found in the cornea and lens as well. Levels of the iron carrier transferrin are high in the aqueous and vitreous humors. The functions of these proteins in other tissues, combined with studies on cultured ocular tissues, genetically engineered mice, and eye exams on patients with hereditary iron diseases provide clues regarding their ocular functions. Iron may play a role in a broad range of ocular diseases, including glaucoma, cataract, AMD, and conditions causing intraocular hemorrhage. While iron deficiency must be prevented, the therapeutic potential of limiting iron-induced ocular oxidative damage is high. Systemic, local, or topical iron chelation with an expanding repertoire of drugs has clinical potential.
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PMID:Iron homeostasis and toxicity in retinal degeneration. 1792 Oct 41

The refracton hypothesis describes the lens and cornea together as a functional unit that provides the proper ocular transparent and refractive properties for the basis of normal vision. Similarities between the lens and corneal crystallins also suggest that both elements of the refracton may also contribute to the antioxidant defenses of the entire eye. The cornea is the primary physical barrier against environmental assault to the eye and functions as a dominant filter of UV radiation. It is routinely exposed to reactive oxygen species (ROS)-generating UV light and molecular O(2) making it a target vulnerable to UV-induced damage. The cornea is equipped with several defensive mechanisms to counteract the deleterious effects of UV-induced oxidative damage. These comprise both non-enzymatic elements that include proteins and low molecular weight compounds (ferritin, glutathione, NAD(P)H, ascorbate and alpha-tocopherol) as well as various enzymes (catalase, glucose-6-phosphate dehydrogenase, glutathione peroxidase, glutathione reductase, and superoxide dismutase). Several proteins accumulate in the cornea at unusually high concentrations and have been classified as corneal crystallins based on the analogy of these proteins with the abundant taxon-specific lens crystallins. In addition to performing a structural role related to ocular transparency, corneal crystallins may also contribute to the corneal antioxidant systems through a variety of mechanisms including the direct scavenging of free radicals, the production of NAD(P)H, the metabolism and/or detoxification of toxic compounds (i.e. reactive aldehydes), and the direct absorption of UV radiation. In this review, we extend the discussion of the antioxidant defenses of the cornea to include these highly expressed corneal crystallins and address their specific capacities to minimize oxidative damage.
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PMID:The role of corneal crystallins in the cellular defense mechanisms against oxidative stress. 1807 95


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