摘要:

Human cataractous glycosphingolipids were isolated and purified according to previously established procedures. Fatty acid analyses of the purified glycosphingolipid revealed the presence of a significant amount of an odd-chain fatty acid. This was confirmed by methane (CH4) chemical ionization mass spectrometry, which showed characteristic ions at m/z 397, 425, 437, and 365. These ions facilitated the determination of molecular weight and the assignment of C25.0(n-penta-cosanoic acid) to this fatty acid in question. This may be the first time that such an unusual distribution of a single odd-chain fatty acid has been shown to occur in a glycosphingolipid from any tissue.

ISSN:0271-3683    

DOI:10.3109/02713688709044499

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Alterations in the vitreo-retinal barrier can modify the exchange of water taking place between the retina and the vitreous body and cause retinal edema to develop. To verify this fact, albino rabbits were subjected to vitrectomies perfusing various intraocular irrigating solutions for various durations. The following conclusions were drawn from these experiments: Ringer's Lactate and physiological saline solutions are more edematogenous than BSS plus; the induced edema is more severe, the longer the perfusion.We have also confirmed that this edema is inhibited by topically administered indomethacin, which proves that in the rupture of blood-retinal barriers during the vitrectomy, prostaglandins play an important role.

ISSN:0271-3683    

DOI:10.3109/02713688709044500

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

In the application of Topcon SL-45 Scheimpflug slit and Neitz CTR retroillumination photography to in vivo documentation of cataractous change, several sources of variance affect the results of each technique. We have measured the between-person, between-photographer, between-focal plane (Neitz), between-photo session, replicate photograph (Topcon), between-image analyst and replicate image analysis variances encountered in in vivo documentation of human cataracts with the Topcon SL–45 and Neitz-CTR cameras and our system of computerized image analysis.

ISSN:0271-3683    

DOI:10.3109/02713688709044501

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Corneal thickness was measured on awakening in both eyes of ten subjects who slept with a silicone elastomer lens in one eye only. The mean corneal edema level with the silicone lens after eight hours of sleep was 2.0±2.0% and was significantly lower (p<0.01) than the level in the eye that did not wear a lens (3.6±2.1%). This indicates that the oxygen level supplied to the anterior cornea during sleep with silicone elastomer lenses is higher than without a lens. We hypothesize that the lower overnight swelling with the silicone lenses is a result of reduced resistance to oxygen flow from the eyelid capillaries to the corneal epithelial cells possibly due to decreased tear film thickness. Other possible explanations include insulating the cornea from the hypo-osmotic shift that occurs with sleep.

ISSN:0271-3683    

DOI:10.3109/02713688709044502

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Intracameral hydrogen peroxide (H2O2) is cleared at a faster rate in young (t 1/2, 93 seconds) than in adult (t 1/2, 109 seconds) rabbits. Extrapolated zero time concentrations of H2O2were 3.3 mM in adults and 3.2 mM in young. The more rapid disappearance of H2O2correlated with greater catalase levels in iris (35%) and corneal endothelium (50%) in young as compared to adult animals. Catalase levels have been found to be reduced in ocular tissues with 3-amino–1H-1,2,4–triazole (3AT) in a dose-related manner up to 6 ml/kg of an intravenous 3M solution. Iris and ciliary processes showed a linear reduction with dose, while corneal endothelium, liver and lung reached near maximal decreases in catalase activity at 2, 4, and 6 ml/kg, respectively. 3AT caused a significant dose-dependent extension of the rate of clearance of H2O2from the anterior chamber, that was directly related to catalase loss. The t 1/2 for H2O2disappearance in adult animals increased from 109 seconds with no 3AT, to 147 seconds after 2 ml/kg 3M 3AT, to 161 seconds after 4 ml/kg 3M 3AT and 184 seconds after 6 ml/kg 3M 3AT. Corneal endothelial oxidized glutathione levels were transiently increased after intracameral hydrogen peroxide. Considering the sum total of all tissues of the anterior segment, specific incremental decreases of catalase generated by intravenous 3AT caused the t 1/2 of H2O2clearance from the anterior chamber to become longer, while the reducing power of anterior segment tissues excluding lens epithelium is related clearly to the systemic dose of 3AT. Protection of anterior segment tissues from oxidants depends on the interplay between the concentration of the oxidant, the availability of reduced glutathione and the activity of catalase.

ISSN:0271-3683    

DOI:10.3109/02713688709044503

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

3-aminotriazole (3AT) is known to reduce catalase levels in ocular tissues when given intravenously or orally. Rabbits were given either 4 ml/kg of a 3M solution of 3AT intravenously or a 2% solution as drinking fluid. Intravenous 3AT administration was followed at 4 hrs by an intracameral injection of hydrogen peroxide (H2O2) to give an aqueous humor concentration of 3.2 mM in young (4–6 weeks of age) and a 3.3 mM in adult (6 months of age) rabbits. Tissues were taken for microscopy at either 6 or 24 hours after intracameral H2O2. Neither oral nor intravenous 3AT alone in adult rabbits, or intravenous 3AT in young rabbits, had any effect on either iris, ciliary process, or corneal endothelial morphology. After oral 3AT in adult rabbits, H2O2caused highly edematous ciliary processes with dilated vessels; corneal endothelial cells were swollen. Previous studies in adult and young rabbits have shown that intracameral H2O2alone caused few morphological changes in young, but marked changes in the adult that correlated with the 35 to 50% lower catalase levels found in iris and corneal endothelium, respectively, in adult ocular tissues. Young rabbits pre-treated with intravenous 3AT, when examined at 6 and 24 hours after intracameral H2O2showed swollen ciliary processes, vessel dilation, alteration of the pigment epithelium and corneal endothelial damage. In non 3AT–treated young rabbits, H2O2caused only minor morphological changes. In adult animals at 6 and 24 hours after intracameral H2O2the ciliary processes were edematous in the absence of 3AT; after intravenous 3AT and intracameral H2O2the changes were even more marked, with very severe swelling of ciliary processes and corneal endothelial damage. It is apparent that the decrease in catalase caused by 3AT allows H2O2to induce damage even in young animals where it usually does not induce morphological changes. In adult animals, the effects of H2O2are enhanced in the presence of 3AT.

ISSN:0271-3683    

DOI:10.3109/02713688709044504

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

The intracellular pH of a normal lens is 6.8 in the cortex and remains unchanged during culture in media buffered at pH 7.2. Incubation of rabbit lenses in calcium enriched media, either at 24°C or 37°C, results in lens opacification provided that the lens pH remains slightly acidic. Opacities are prevented in cultured lenses with an alkaline interior (pH 7.1–7.3) despite the accumulation of calcium (1.3 mM). The mechanism by which an intracellular pH shift from 6.8 to 7.1 prevents opacification in the presence of excess calcium is not known, but does not appear to depend upon the total level of bound calcium. This study provides the first data that opacification caused by calcium is associated with lens pH.

ISSN:0271-3683    

DOI:10.3109/02713688709044505

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

We have used quasielastic light scattering to detect and quantitatively characterize the molecular changes associated with the early stages of cataractogenesis in the living human lens. The autocorrelation function of the fluctuations in the light scattered by the lens shows the presence of two major species responsible for the scattering. The first, fast diffusing species (f), has a diffusivity of∼3×10-7cm2/sec and corresponds to the alpha crystallin proteins. The second, slow diffusing species (s), has a diffusivity of∼10-9cm2/sec and corresponds to the diffusivity of a large aggregate. The intensity of light Ifand Isscattered into the collection optics by each of these species was also measured. We studied a group of 49 individuals ranging in age from 21 years to 82 years. In this group 40 presented with pre-operative cataract development. In this patient population we found that regardless of age, or position in the lens that a plot of Itot= If+Isversus Iscould be well fitted by a straight line with a slope less than unity and a positive intercept Ifo. It has been possible to explain this finding using a two state model for the molecular changes associated with early cataractogenesis. In this model the proteins in the slow diffusing species are aggregates each containing a definite number of rapidly diffusing proteins. The early development of cataract is represented by the redistribution of protein between the unaggregated form (f) and the aggregated form (s). The prediction for the relationship between Itotand Isbased on this two state model is in very good agreement with our experimental data. Indeed the measured position of the point (Itot, Is) along this line provides a sensitive, and quantitative measure of the degree of cataract development at any selected location in the lens.

ISSN:0271-3683    

DOI:10.3109/02713688709044506

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

The effect of sodium hyaluronate on the production of migration inhibitory factor (MIF) was studied in a two step MIF-assay.High molecular weight sodium hyaluronate (100 ug/ml), added during the inductory step of the MIF-assay, inhibited the production of MIF. The inhibitory effect did not appear to be due to physical factors such as steric hindrance, which may prevent mitogen binding, since cells pre-activated with phytohemagglutinin A (PHA) did not produce MIF when incubated in the presence of sodium hyaluronate. The inhibitory effect was still measurable when the sodium hyaluronate was added upto two hours after stimulation of the mononuclear cells with PHA. Inhibition was also found when the cells were preincubated with sodium hyaluronate, and washed prior to mitogen stimulation. Sodium hyaluronate could only be removed from the cells by incubation with hyaluronidase or by incubation of the cells for at least two hours in culture medium, whereafter the cells could be stimulated to the same extent as normal untreated cells to produce MIF.This inhibitory effect on cytokine production may explain the reduced inflammatory reactions found both in vivo and in vitro in the presence of sodium hyaluronate.

ISSN:0271-3683    

DOI:10.3109/02713688709044507

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Staining techniques and scanning electron microscopy (SEM) were used to assess damage to the endothelial cells following corneal storage. The aim was to establish whether these assays are useful in the assessment of endothelial integrity following corneal storage.Four groups ensured a range of normal and damaged endothelial cells: 1) fresh; 2) stored for 7 days in a moist chamber; 3) stored by the cryo-preservation method of Capella and Kaufman; 4) damaged by rapid freezing with a cryoprobe. Trypan blue (TB), nitroblue tetrazolium (NBT), acridine orange (AO), fluorescein diacetate (FDA) and ethidium bromide (EB), were used to stain the endothelial layer. SEM was carried out on duplicate samples.Staining with NBT resulted in low cell counts due to loss of cells. There was no significant difference between the extent of damage measured by TB, AO or FDA, but it was shown that staining with FDA and EB can distinguish between damaged and intact cells. Tissue stored for 7 days in a moist chamber had a reduced number of intact cells compared to fresh tissue, and tissue stored by the Capella and Kaufman technique gave a reduced number of intact cells compared to both these control and storage groups. SEM showed surface perforation was characteristic of injured cells, rather than complete disruption.FDA has a theoretical advantage over the other stains, and should provide a more accurate appraisal of defects of cell membrane integrity. For this reason, the use of FDA with EB to stain the endothelium, with SEM carried out on duplicate samples, were preferred as assays to use in the development of corneal storage.

ISSN:0271-3683    

DOI:10.3109/02713688709044508

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor