Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pellucid marginal degeneration of the cornea is a bilateral, clear, inferior, peripheral corneal-thinning disorder. Protrusion of the cornea occurs above a band of thinning, which is located 1 to 2 mm from the limbus and measures 1 to 2 mm in width. American ophthalmologists are generally not familiar with the condition because most of the literature concerning pellucid degeneration is European. Four cases are described. This condition is differentiated from other noninflammatory cornel-thinning disorders such as keratoconus, keratoglobus, keratotorus, and posterior keratoconus. It is also differentiated from peripheral corneal disorders associated with inflammation such as Terrien's peripheral corneal degeneration, Mooren's ulcers, and ulcers from connective tissue disease.
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PMID:Pellucid marginal corneal degeneration. 35 10

Eyes from cardiomyopathic hamsters (UM-X7.1 strain) were examined histologically for evidence of ocular defects. Changes observed included microphthalmia, scleral ectasia, scleral rupture, keratoconus, retinal detachment, retinal dysplasia, retinal fragmentation, retinal thinning, fibrosis of iris and ciliary body, ectopia lentis, and cataract formation. Lesions characteristic of cardiomyopathic hamsters were observed in the myocardium and skeletal muscle. This strain may be a suitable animal model to study the pathogenesis of ocular changes seen in certain congenital connective tissue disorders in man.
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PMID:Ocular abnormalities in the myopathic hamster (UM-X7.1 strain). 41 Jul 51

Keratoconus is a disease that results in thinning and ectasia of the central cornea. Cultures of corneal stromal cells from patients with keratoconus were established and the synthesis of glycosaminoglycans compared with the synthesis of glycosaminoglycans by normal human corneal stromal cells in culture. Keratoconus and normal control cell cultures were incubated with sodium [(35)S]sulfate and [(3)H]glucosamine for 4 h. After incubation, the labeled glycosaminoglycans were isolated from the medium fractions and cells. Keratoconus and normal control cultures synthesized similar amounts of sulfated glycosaminoglycans independent of the age of donors and(or) the number of subcultures. In contrast to normal control cultures, most of the newly synthesized glycosaminoglycans produced by keratoconus cells were found in the growth medium and much less were in the cell layer. Treatment with glycosaminoglycan-degrading enzymes followed by paper chromatography showed that keratoconus cells, as normal control cells, produced hyaluronic acid and various sulfated glycosaminoglycans. The production of cell layer-related heparan sulfate was markedly reduced in keratoconus cultures. Because heparan sulfate has been shown to be associated with cell surfaces, the decreased heparan sulfate content could reflect changes at this location.
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PMID:The synthesis of glycosaminoglycans by cultures of corneal stromal cells from patients with keratoconus. 43 19

Posterior keratoconus is a rare corneal disorder characterized by a total or localized noninflammatory thinning of the cornea. In front of a conical protrusion of the posterior corneal curvature, there is a thinned stroma and nonprotruding anterior surface. A corneal button from a patient with bilateral posterior keratoconus was studied by light and electron microscopy. Descemet's membrane, particularly in the area of stromal thinning, demonstrated abnormal anterior banding, a multilaminar configuration, and localized posterior excrescences. These alterations suggest an early pathogenetic mechanism, which probably originated prior to the fifth or sixth month of gestation.
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PMID:Posterior keratoconus. 69 25

Fifteen corneal buttons were removed at keratoplasty from patients with keratoconus who had previously undergone thermokeratoplasty (TKP). The buttons were studied with light microscopy, in an attempt to analyze the type of changes produced by TKP. The principal histologic findings in patients with retarded epithelial healing (8 of 15) included epithelial thinning, bullous keratopathy, thickening of the epithelial basement membrane, and frequent destruction of Bowman's membrane. More severely affected patients showed asceptic stromal necrosis and fibrinous iritis with hypopyon. A poor visual result in patients with normal epithelial healing (7 of 15) was caused by superficial stromal scarring or persistent inflammatory infiltrate. Vascularization was seen in only one patient.
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PMID:Alterations in corneal morphology following thermokeratoplasty. 79 73

Posterior keratoconus is an unusual abnormality of the cornea generally classified as one of the anterior chamber cleavage anomalies. It is characterized clinically by the presence of a circumscribed or generalized corneal thinning with posterior depression of the cornea and is considered distinct from keratoconus. Although patients with posterior keratoconus may have visual complaints clearly related to their abnormal corneas, the surface topography of these corneas has not been studied in detail. Keratometry and photokeratoscopy provide an incomplete picture of the surface geometry of posterior keratoconus. We utilized computer assisted topographic analysis to study the cornea of a patient with posterior keratoconus. The Topographic Modeling System demonstrated that the patient's cornea showed a central steepened "cone" coincident with the area of circumscribed posterior keratoconus as well as paracentral flattening. This report documents the topographic abnormality in this rare disorder.
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PMID:Corneal topography of posterior keratoconus. 142 57

During examination of 131 penetrating keratoplasty specimens from patients with keratoconus obtained in an 11-year period, we observed two histopathologic variants based on the appearance of Bowman's layer and the corneal epithelium. "Typical" keratoconus specimens had multiple breaks in Bowman's layer and central epithelial thinning, whereas "atypical" corneas lacked breaks in Bowman's layer and had less thinning of the central epithelium. Ninety-five corneas were from patients who underwent grafting in only one eye. Seventy-six (80%) of these corneas were "typical" and 19 corneas (20%) were "atypical" in appearance. Both variants had similar degrees of central stromal thinning. Patients with "typical" and "atypical" corneas differed demographically by race only; 49% of "typical" and 95% of "atypical" corneas were from white individuals. Thirty-six corneas were from 18 patients who underwent bilateral penetrating keratoplasty. The histologic appearance of these corneal pairs was concordant in 13 patients and discordant (one "typical" and one "atypical" cornea) in five patients. Statistical analysis indicated that this distribution is not significantly different from that predicted by chance and suggests that "typical" and "atypical" corneas are manifestations of the same disease process.
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PMID:Histopathological variation in keratoconus. 146 18

The aim of this study was to determine any differences in the collagen molecular and fibrillar packing, or the arrangement of the proteoglycans along the fibril axis, in the stroma of keratoconus and control corneas. High and low-angle x-ray diffraction patterns from the fibrillar and molecular packing of collagen in keratoconus and control corneas were obtained using a synchrotron radiation source. The results indicate no difference in interfibrillar spacing between keratoconus and control corneas at normal physiological hydration, or over a range of hydrations (H = 1-11). This unambiguously demonstrates that the thinning of the stroma that occurs in keratoconus is not a result of closer packing of the collagen fibrils in the stroma. Intermolecular spacings were shown to be significantly (P less than 0.001) lower in keratoconus corneas at normal physiological hydration and over a range of hydrations (H = 1-11). Meridional patterns from the axial distribution of electron density along the collagen fibrils were obtained from untreated control and keratoconus corneas and from the corneas after their proteoglycans were stained with cupromeronic blue. Analysis of the integrated intensities of the first nine orders of these reflections show there is a difference in the staining behavior of collagen-associated proteoglycans in control and keratoconus corneas. Determination of the electron density vectors along the collagen fibrils of cupromeronic blue-stained corneas by the use of Patterson functions indicates that the keratoconus corneal stroma has a specific, ordered proteoglycan that is present in lower numbers along the collagen fibrils, and that it stains less with cupromeronic blue or is in a more disordered arrangement than in the controls.
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PMID:Synchrotron x-ray diffraction studies of keratoconus corneal stroma. 155 73

We studied 3 eyes from 2 patients with posterior keratoconus. One patient (a 17-year-old female) had posterior keratoconus bilaterally and the other (a 8-year-old male) had posterior keratoconus in one eye and Peters' anomaly in the contralateral eye. Slit-lamp biomicroscopy disclosed localized thinning with stromal haze underlying the endothelium in the central cornea. Photokeratoscopy revealed no abnormalities suggestive of anterior keratoconus. Wide-field specular microscopy showed the endothelial cells with normal cell density (approximately 3500 cells/mm2) and morphology in both the peripheral and central corneas (adjacent to the hazy areas).
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PMID:[Two cases of posterior keratoconus]. 187 24

Keratoconus, a bilateral corneal disease, is characterized by modifications in corneal shape and thinning of the stroma. From a biochemical point of view, a decrease in collagen content, probably due to the high collagenase activity, has been reported. Gamma Interferon (gamma-IFN), Tumor Necrosis Factor (TNF), and Interleukin 1 (IL1) are peptide regulatory factors involved in immunological responses, but they also play a role in the synthesis of collagen and prostaglandin E2 by fibroblasts. In these experiments, we have determined the number of membrane binding sites for gamma-IFN, TNF, and IL1, and the dissociation constant (Kd) for each radiolabelled ligand. All experiments were carried out on cultured corneal stromal cells. Data from normal human corneas and from keratoconus were compared. No differences were found concerning gamma-IFN and TNF binding sites between normal corneas and keratoconus, while fibroblasts from keratoconus proved to bear four fold more IL1 binding sites than normal fibroblasts, with similar Kd.
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PMID:Binding sites for human interleukin 1 alpha, gamma interferon and tumor necrosis factor on cultured fibroblasts of normal cornea and keratoconus. 191 96


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