ISSN:0030-3755    

DOI:10.1159/000310778

出版商:S. Karger AG    

年代:1997

数据来源: Karger

ISSN:0030-3755    

DOI:10.1159/000310779

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Studies of the effects of glucocorticoid (GC) and oxidative stress stimuli in differentiated cultures of human trabecular meshwork (HTM) cells have provided the rationale for our studies of a major new gene termed TIGR (trabecular meshwork inducible GC response). The TIGR clone was isolated by differential library screening using selection criteria based on the induction pattern of a new protein/glycoprotein found in HTM cultures after prolonged but not brief exposure to GCs. This GC induction patter matched the time course and dose response required for intraocular pressure elevation in patients receiving corticosteroids. The very large, progressive induction of TIGR combined with specific structural features of its cDNA suggested that TIGR should be considered a candidate gene for outflow obstruction in glaucoma. Among the properties of TIGR cDNA were a signal sequence for secretion, several structural features for interactions with glycosaminoglycans and other glycoproteins and putative sites for cell surface interactions. In addition, the leucine zippers in the structure were related to TIGR-TIGR oligomerization that was shown to occur with native and recombinant TIGR protein. The verification that TIGR was a major stress response protein in HTM cells following hydrogen peroxide (or phorbol esters) exposure provided a potential link between GC and oxidative mechanisms thought to be involved in glaucoma pathogenesis. Pharmacological evaluation showed that basic fíbroblast growth factory and transforming growth factor β decreased the GC induction of TIGR, and certain nonsteroidal anti-inflammatory drugs protected against both GC- and oxidation-induced stress responses in HTM cells. Our recent studies of TIGR’s genomic structure have shown motifs in the promoter region that suggest a basis by which multiple hormonal/environmental stimuli can regulate TIGR production and by which putative genetic alterations could lead to an overexpression of the protein. Further application of cell biology/biochemistry, molecular biology, genetic and histological approaches will be helpful in understanding the role of TIGR in different glaucoma syndro

ISSN:0030-3755    

DOI:10.1159/000310780

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Trabeculectomy specimens from 11 patients with juvenile glaucoma were studied by electron microscopy and quantitatively evaluated. In all cases, large amounts of extracellular material arranged in a fingerprint-like pattern, resembling basement-membrane-like material (FBM) was found, similar to that described in steroid-induced glaucoma. This material was found mainly within the inner cribriform and outer corneoscleral regions of the trabecular meshwork, and caused the cribriform layer to be greatly thickened. FBM was also intimately associated with trabecular cells, which frequently appeared activated. In 3 cases, there was also an increase in fine fíbrillar material which resembled that found in eyes with steroid-induced glaucoma. The amount of sheath-derived plaque material, which is increased in primary open angle glaucoma, was greatly increased in the subendothelial layer adjacent to Schlemm’s canal.

ISSN:0030-3755    

DOI:10.1159/000310781

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Trabecular meshwork cells are actively phagocytic and may function to keep the drainage pathways free of cellular debris, pigment and other material. A decrease in phagocytic capacity has been proposed in the pathogenesis of glaucoma. This study was performed to compare the phagocytic capability of the human trabecular meshwork in glaucomatous and normal human eyes. The anterior segments of 6 donors with glaucoma (primary open-angle glaucoma, POAG: 5 donors; pseudoexfoliative glaucoma, PEX: 1 donor) and 6 normal donors were placed in perfusion organ culture. During the final 24 h of culture, latex microspheres, labeled with F1TC and coated with antibodies, were perfused into the anterior segments. Eyes were then fixed, the trabecular meshworks were treated with a rhodamine-labeled secondary antibody, sectioned and the number of ingested beads determined with the laser scanning confocal microscope. Nuclei were quantitated and used to calculate the phagocytic index of each eye (number of ingested beads/number of nuclei). Anterior segments of glaucomatous donors were cultured for 1-3 days, as a preliminary culture study had revealed that culture of glaucomatous anterior segments is successful in only 50% when cultured for 21 days. Specimens of normal donors were cultured for 21 days. Ingested beads appeared green and could be differentiated from noningested beads, which appeared red, using appropriate wavelengths of the laser. Bead ingestion was confirmed with electron microscopy and the use of a secondary antibody labeled with horseradish peroxidase. Ingestion rates appeared similar among all three groups of eyes: POAG, 3.8 beads/cell; PEX, 3.3 beads/cell; normal, 3.5 beads/ cell. No evidence of significant migration or loss of trabecular cells was noted. Cell counts were not significantly different: POAG, 127 ± 40 cells/section; normals, 136 ± 49 cells/section. In conclusion, the phagocytic ability of the trabecular meshwork appears similar between eyes with POAG and normal eyes in perfusion organ culture. Cell loss after phagocytosis was not observed in these single-exposure experiments.

ISSN:0030-3755    

DOI:10.1159/000310782

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Measurements of isometric tension were performed on isolated trabecular meshwork (TM) and ciliary muscle (CM) strips of the bovine eye. Anterior segments of bovine eyes with well-preserved TM were perfused to measure outflow rate. (1) Bumetanide (10––4 mol/l) and hydrochlorothiazide (10––4 mol/l) did not change the contractility of TM and CM strips in the presence or absence of carbachol. Ethacrynic acid dose-dependently relaxed TM and CM strips precontracted either by carbachol or endothelin. (2) Cytochalasin D totally relaxed TM and CM strips precontracted by carbachol. The outflow rate almost doubled after application of cytochalasin D. (3) The effects of various modulators of K+ and Ca2+ channels are summarized. Carbachol and endothelin are postulated to modify nonselective cation channels. An effective blocker of nonselective cation channels (flufenamic acid) relaxed TM and CM precontracted by carbachol or endothelin. These relaxing effects were independent of the relaxing effects of ethacrynic acid and isosorbide dinitrate. (4) Evidence for the presence of various transporters and receptors in TM cells is summarized. (5) The TM per se is a contractile element which is involved in the regulation of aqueous humor outflow. The contractility of TM and CM cells is differently mo

ISSN:0030-3755    

DOI:10.1159/000310783

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

The choroid of primates possesses an elaborate nitrergic nerve fiber plexus containing a great number of ganglion cells. Postganglionic nerve fibers innervate mainly the choroidal vasculature. In addition, the choroid contains an elastic muscular system closely associated to the vasculature. The goal of the present investigation was to analyze how sustained IOP elevation would affect the choroidal vasculature with its specialized innervation and the adjacent retina. For this purpose the posterior eye segment of 15 rhesus monkeys which after laser coagulation of the trabecular meshwork developed elevated IOP up to 4 years were studied using immunohistochemical and histochemical methods, and scanning electron microscopy of corrosion casts. The most striking finding was a significant reduction of choroidal thickness and loss of choroidal ganglion cells and nerve fibers, especially in the central portion of the choroid. Corrosion casts of the choroidal vasculature showed a slight decrease in capillary density and a decrease in length of the arterioles in glaucomatous eyes. Whole mount preparations of the retina stained for NADPH diaphorase revealed a significant reduction in positively stained amacrine cells, reduction in diameter of arterioles and changes in the staining pattern of the retinal vasculature, particularly in the perimacular region.

ISSN:0030-3755    

DOI:10.1159/000310784

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Measurements of retinal leukocyte velocity were made in single eyes of 6 glaucomatous adults and 9 normal subjects at each of 4 discrete levels of IOP elevation assigned according to the characteristics of prior pattern-evoked cortical potential pressure tolerance measurements. Glaucomatous eyes failed to demonstrate any stabilization in retinal leukocyte velocity at pressures above 45 mm Hg, with velocities 33% lower than normal for a comparable degree of IOP elevation (p < 0.012). Even at baseline IOP, leukocyte velocity was 27.2% slower in the treated glaucomatous eyes than in normal control eyes (p≤ 0.013), despite comparable baseline IOP levels in both groups.

ISSN:0030-3755    

DOI:10.1159/000310785

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Experimental glaucoma was induced in 1 eye of 6 cynomolgus monkeys by laser treatment of the trabecular meshwork. In 5 of the 6 monkeys the increased intraocular pressure (IOP) caused marked glaucomatous damage in the experimental eye. Ocular blood flow was determined with labeled microspheres 4 years after the laser treatment. IOP was regulated with an external reservoir. With the same perfusion pressure in both eyes no statistically significant difference was observed between the 2 eyes for total ocular blood flow or for blood flow through any of the ocular tissues. Total ocular blood flow was 343.5+61.4 mg/min (mean ± SEM) in the control eye and 385.3 ± 107.7 mg/min in the experimental ey

ISSN:0030-3755    

DOI:10.1159/000310786

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Comprehensive understanding of the three-dimensional structure of the extracellular matrix (ECM) of the lamina cribrosa is central to understanding its role in health and disease, particularly how changes in configuration might precipitate nerve fibre death in glaucoma. Research until recently has relied almost entirely on light and scanning electron microscopy (SEM) to investigate the ECM of the lamina cribrosa. In this paper, we review the contribution of these methods to current understanding of the three-dimensional structure of the lamina ECM, highlight their potential weaknesses and emphasise that there is still much to be revealed about the structure of the lamina ECM. We then describe our development of confocal microscopy and computer reconstruction as a new and alternative method of investigating the three-dimensional structure of the lamina ECM. We show how optical sectioning allows the confocal microscope to acquire three-dimensional images of the lamina ECM without the degree of tissue disruption associated with preparation for SEM and demonstrate the versatility of analysis of these images by computer reconstructive software. A case is made for confocal microscopy and computer reconstruction contributing to our understanding of this important but complex and delicate structure.

ISSN:0030-3755    

DOI:10.1159/000310787

出版商:S. Karger AG    

年代:1997

数据来源: Karger