摘要:

Rainbow trout (Oncorhynchus mykiss) were used to model the solar radiation-induced cataract that occurs in hatchery-reared lake trout (Salvelinus namaycush). Rainbow trout eyes were exposed to wideband predominantly UVB radiant energy from a filtered 1000W xenon source. Lenticular damage was assessed and classified and comeal damage noted. Lenticular theshold radiant exposure was 0.48 J.cm-2which is in the same range as the mammalian lens. Permanent lenticular damage occurred at radiant exposure levels approximately twice the theshold for lenticular radiant exposure (also similar to the mammalian response). Slit-lamp and scanning electron microscopical results support the theory of post-exposure anterior subcapsular epithelial cell damage, lens fibre swelling, and eventual rupture, leading to areas of lower refractive index in the anterior subcapsular region of the lens.

ISSN:0271-3683    

DOI:10.3109/02713689308999477

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

The vitreous of most mammals contains low concentrations of three polymeric macromolecules, collagen, hyaluronan and beaded fibrils. To determine whether the beaded fibrils may have a localized function, or whether all three of these polymers could contribute to the structure and/or strength of the vitreous gel, the distribution of collagen and beaded fibrils in the central and cortical regions of the bovine vitreous was studied. The polymers were separated by isopycnic centrifugation and analyzed to determine the protein ratios. Both collagen and beaded fibrils are present in each region, but the concentration of the beaded fibril is greatest in the posterior cortical volume.

ISSN:0271-3683    

DOI:10.3109/02713689308999478

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

The effect of glutathione (GSH) isopropyl ester on the progression of X-ray-induced cataract was investigated in rats. Intraperitoneal administration of 20 mg/kg GSH isopropyl ester, three times weekly, 1 day after a single irradiation dose delayed the progression of X-ray-induced cataracts significantly. The amount of non-protein SH groups and the Na+/K+ratio in the lenses of drug-treated rats were maintained at the normal levels even 27 weeks after irradiation. Posttreatment with the drug resulted in a significantly lower level of malondialdehyde in the irradiated lenses than in the non-treatted lenses.When 500 mg/kg GSH-isopropyl ester was administered by i.p. injection to normal rats, the GSH-ester was detected in plasma and aqueous humor after 15 min. In the lenses of the GSH-isopropyl ester-injected rats, the GSH level was 120% of that in the non-treated rats after 4 h, suggesting that GSH-isopropyl ester is transported from the aqueous humor to the lens and there converted to GSH after about 4 h. Our observations lead us to conclude that the delay of X-ray-induced lens opacity progression is due to maintenance of normal lenticular GSH levels achieved by post-irradiation administration of GSH-isopropyl ester.However, continuous administration of 100 mg/kg after irradiation had no effect on the progression of cataracts induced by X-rays.

ISSN:0271-3683    

DOI:10.3109/02713689308999479

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

A number of classifications schemes for the grading of lens opacities have been developed but none of them have been examined for reliability and validity in prospective or longitudinal studies. The purpose of this study was to develop and test a method for determining progression which was sufficiently sensitive to true change and insensitive to measurement error. The method consists of assessing various sources of measurement error, determining the likely magnitude of the error, and setting boundaries for changes in opacification which incorporate this error. Measurement error was assessed in 203 nuclear lens photographs graded using a decimal system and 136 cortical lens photographs graded in 1/16th area. 95% confidence intervals were calculated of the distribution of differences between photographs and graders and the width of this intervals defined as measurement error. The magnitude of the measurement error was±0.7 units for nuclear opacities and±2/16 for cortical opacities. The utility of this approach was tested in a series of 84 clinic patients followed at irregular intervals for up to 3 years. Only one eye showed“improvement”and progression rates ranged from 1.8 to 5.5% for nuclear opacities and 0 to 7.4% for cortical opacities in this clinic-based series. This approach appears to be useful for discarding noise and enabling the assessment of progression for use in longitudinal studies.

ISSN:0271-3683    

DOI:10.3109/02713689308999480

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Flat bleached preparations of retinal pigment epithelial (RPE) cells from foveal, temporal posterior pole, and temporal equatorial fundus locations of 20 normal human eyes from donors age ranked from 13 to 96 years were analyzed for density, and 10 were analyzed for area, hexagonality and polymegathism. These factors were related to fundus locations and age. Foveal RPE cells were significantly more dense and more hexagonal in eyes from younger donors. Loss of hexagonality in the fovea, but not elsewhere, was correlated with increasing age. As the eye ages, foveal RPE cells selectively lose unique morphologic characteristics and resemble nonfoveal cells. These morphologic changes resemble other pathologic features of age-related degeneration in their proclivity for the fovea and posterior pole.

ISSN:0271-3683    

DOI:10.3109/02713689308999481

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Scleral tissue from the region of the human macula was studied by the immunogold labeling technique (cryoultramicrotomy and LR white resin embedding) in an attempt to identify the fine structural distribution of collagen types I–VI. Labeling of the striated collagen fibrils suggested colocalisation of collagen types I, III and V with type V occurring at the fibril surface. Both types V and VI collagen were localised to filamentous strands in the interfibrillar matrix. Collagen types II and IV were absent from the scleral stroma.

ISSN:0271-3683    

DOI:10.3109/02713689308999482

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Specific and high affinity binding of the potent muscarinic cholinergic antagonist, [3H] quinuclidinylbenzilate ([3H] QNB) was observed using intact native and cultured adult human corneal endothelium (HCE). Specific binding was proportional to radioligand concentration between 0.03 and 5 nM, indicating a maximal binding capacity (Bmax) of 130 fmol of [3H] QNB/mg protein and a dissociation constant (Kd) of 0.3 nM. Atropine competed effectively with [3H] QNB for binding sites; requiring 3 nM to inhibit 50% of the binding of 1 nM [3H] QNB. Carbachol also competed with [3H] QNB at higher concentrations, but nicotine did not affect [3H] QNB binding at levels up to 1 mM. [3H] QNB binding was also observed in cultured cells of adult human, rabbit, and bovine corneal endothelium.Native and cultured HCE were affinity labelled using tritium-labelled propylbenzilylcholine mustard (PBCM). Separation of the proteins in affinity labelled native and cultured tissue by SDS - polyacrylamide gel electrophoresis (SDS-PAGE) showed that only one protein in each preparation, of 60 and 55 kilodaltons (kDa), respectively, was specifically radiolabelled.These data indicate that the corneal endothelium of human and several animal species exhibit muscarinic cholinoceptors.

ISSN:0271-3683    

DOI:10.3109/02713689308999483

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

H2O2stress is shown to produce cataract in cultured rat lenses. The loss of transparency begins in the equatorial region within 24 hours and the entire superficial cortex is opaque by 96 hours. No involvement of the nuclear region is observed. However after an additional 48 hours, the nuclear region becomes opaque. The loss of transparency is accompanied by a large uptake of H2O which occurs gradually over the 96 hour period, complete loss of glyceraldehyde phosphate dehydrogenase (GPD) activity, almost complete loss of non-protein thiol and a slight decrease in protein thiol. Control lenses show no change other than the establishment of a new non-protein thiol base line approximately 60% lower than 0 time levels. The Alcon glutathione peroxidase type mimic, AL-3823A, completely eliminates almost all of the H2O2induced effects and the lens remains transparent.Utilizing a more severe photochemical model than may be anticipated physiologically with 10μM riboflavin and exposure to daylight fluorescent lamps, significant concentrations of superoxide and low levels of OH•are produced as well as extraordinarily high concentrations of H2O2ranging from about 400 to 1000μM. As with the H2O2model, opacification begins at the equator but the cataract develops more rapidly, the lens being completely opaque by 68 hours. Hydration, GPD activity, non-protein and protein thiol all decrease more rapidly than in the H2O2model. AL-3823A prevents loss of transparency until approximately 92 hours and markedly decreases changes in other parameters. At 92 hours, slight loss of transparency is observed. Catalase is somewhat less effective. AL-3823A is shown to also significantly decrease superoxide levels.The marked delay in the onset of changes in lens biochemistry and physiology in the severe photochemical stress model and the maintenance of normal parameters in the H2O2model in the presence of AL-3823A suggests that such compounds may prevent cataract caused by oxidative stress under physiological conditions.

ISSN:0271-3683    

DOI:10.3109/02713689308999484

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

New Zealand white rabbits have a circadian rhythm of intraocular pressure; pressure is higher during the dark than during the light. We explored the possiblity that the dark phase increase of serum and/or ocular melatonin plays a role in regulating the rhythm of intraocular pressure. Exogenous melatonin was delivered by four routes: topical application (0.1 and 10μg), intravenous injection (1μg), intravitreal injection (9μg) and intra-arterial infusion (50 ng and 1μg). Melatonin delivered by these routes did not increase intraocular pressure. We also measured the concentration of melatonin in the aqueous after unilateral intra-arterial infusion to confirm that melatonin delivered by this route reached the eye. The concentration was 419±99 and 109±17 pg/ml (n = 8, p<0.025) in the ipsilateral and contralateral eyes, respectively. The concentration of melatonin in the aqueous after intra-arterial infusion of saline was less than the sensitivity of the assay (<16 pg/ml, n = 6). The results of these experiments indicate that melatonin does not increase IOP significantly under the experimental conditions employed in this study.

ISSN:0271-3683    

DOI:10.3109/02713689308999485

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

NCAM is present in the plasma membranes of human and rat lens epithelial cells and superficial fiber cells. The predominant isoform in epithelial cells is NCAM 140, while NCAM 120 appears only in the superficial fiber cells. The immunofluorescence patterns are consistent with a decreasing concentration of NCAM associated with fiber cell differentiation.

ISSN:0271-3683    

DOI:10.3109/02713689308999486

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor