Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0086543 (cataract)
 29,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Several osmotic cataract models as well as human diabetic lenses were tested by nuclear magnetic resonance spectroscopy and imaging. Both longitudinal (T1) and transverse (T2) relaxation times increased with increase in lens hydration. Therefore proton magnetic resonance imaging (MRI) can be used to detect changes of the biophysical environment of water proton in the lens. T2-weighted imaging sequence (spin-echo) can be used to differentiate lenses with hydrational changes since they exhibit higher signal intensity (because of long T2) than normal lenses at the same TE (echo time). A greater contrast can be achieved with the inversion-recovery sequence, which, in addition to contribution from T2, also incorporates T1 and proton density terms. Proton MRI is potentially useful for the detection of pre-cataractous changes.
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PMID:Proton magnetic resonance imaging of the ocular lens. 342 3

Normal and cataractous lenses were separated mechanically into lens equator and inner cylinder and the latter then sectioned in a freezing microtome. Fractions with 120-140 sections each were collected representing single lens layers, and the content of water-soluble and insoluble proteins was determined. Protein profiles for each lens layer were obtained by means of isoelectric focusing in special agarose gels. Using this microsectioning technique, it was possible to demonstrate differences in the protein distribution in single layers of both normal and cataractous human lenses. Comparison of the protein profiles of the normal lens and the lenses of different cataract morphology used in this study demonstrates the potential usefulness of this methodology for future research with cataract lenses.
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PMID:Correlation of Scheimpflug photography of the anterior eye segment with biochemical analysis of the lens. Application of a frozen-sectioning technique to investigate differences in protein distribution of single lens layers. 351 71

The effect of (1-benzoyl-1H-indazol-3-yl)oxylacetate L-Lysine (bendazac-lysine) on some enzymatic activities involved in the metabolism of reduced glutathione (GSH) was studied in the rabbit lens during developing cataract induced by a single dose of X-rays (2000 rads). The specific activities of glutathione reductase (G.R.), glutathione peroxidase (GSH.Px) and glutathione S-transferase (GSHS-tr.) do not change following irradiation and treatment with bendazac-lysine. The activity of the same enzymes expressed as a function of water soluble proteins (WSP) per lens significantly decreases (P less than 0.01) as compared to controls in the irradiated lens not treated with bendazac-lysine (ILNTB) at the 8th week, whereas no significant decrease as compared to controls is observed in the irradiated lens treated with bendazac-lysine (ILTB). In the ILNTB the specific activity of glucose-6-phosphate dehydrogenase (G6PDH) is reduced by 10% after 0.3 weeks and by 29% after 12 weeks. In the ILTB the specific activity of G6PDH is reduced by 8% after 0.3 weeks and by 14.5% after 12 weeks. The specific activity of superoxide dismutase (SOD) in the ILNTB is reduced by 19% after 0.3 weeks and reached 31% after 12 weeks. In the ILTB the specific activity of SOD is reduced by 11% after 0.3 weeks and 19.8% after 12 weeks. The mechanism of protective effect of bendazac-lysine on cataract is discussed.
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PMID:Effects of bendazac L-lysine salt on some metabolic enzymes of glutathione in the rabbit lens after X-irradiation. 361 May 98

Among various substances used for intraocular tamponade in the treatment of vitreous opacity and complicated retinal detachment, silicone oil is superior to hyaluronic acid or sulfur hexafluoride. Its low gravity and hydrophobic nature permit good tamponade effect to be obtained and its high transparency allows us to detect remnant vitreous traction in the far periphery and/or retinal tears. Furthermore, preretinal membrane can be peeled off easily after silicone oil removal. The hydrophobic nature of silicone prevents clouding due to postoperative hemorrhage and fibrin reaction. It should also be stressed that intravitreal silicone oil suppresses iridial rubeosis or prevents its development. However, the use of silicone has limitations, since it gives rise to various complications that include pupillary block glaucoma, secondary glaucoma, cataract formation and corneal complications including band-shaped keratopathy. Pupillary block in aphakic eyes can be prevented by placing peripheral iridectomy at the 6 o'clock position, since silicone is lighter than water. After silicone injection, glaucoma is more often seen in diabetic aphakic eyes than in phakic or nondiabetic eyes. On the other hand, corneal complications were less frequent in diabetic than in nondiabetic eyes; in nondiabetic eyes the complications were more frequent in aphakic than in phakic eyes. Due to possible complications, silicone should be removed after a certain follow-up period, during which time detection and management of the causes of redetachment of the retina are possible due to the high transparency of silicone.
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PMID:Usefulness and limit of silicone in management of complicated retinal detachment. 362 73

The concentration of the free aromatic amino acids tryptophan and tyrosine, the antioxidant uric acid and some unidentified compounds have been determined in the water-soluble extracts of parts from clear and nuclear-cataractous human lenses. With age (29-90 years) and cataract formation, associated with increasing nuclear pigmentation, no significant changes were observed in content of tryptophan, tyrosine and uric acid. Furthermore, these compounds did not show variation in distribution within the lens. An unidentified fluorophore, excitation and emission maxima of 345 and 425 nm, respectively, increases significantly in content with nuclear cataract formation, especially in the nucleus. Another unidentified, presumably aromatic compound shows a striking age-related decrease.
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PMID:Distribution of aromatic and fluorescent compounds within single human lenses. 365 75

(1) Changes with age in the Young's modulus of elasticity of human lens capsule and Bruch's membrane have been determined. In lens capsule the modulus decreases with age whereas in Bruch's membrane it increases. (2) Changes with age in the hydraulic conductivity of the human lens capsule and Bruch's membrane have also been determined and again show opposite changes with age. In the former membrane the hydraulic conductivity increases while in the latter it decreases. (3) The ageing changes in the respective membranes indicate that, in man, some time after 100 years in all cases the lens capsule would have a similar hydraulic conductivity to lenses with advanced cataract, while in the same subject Bruch's membrane would have lost its permeability to water.
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PMID:The influence of age on some ocular basement membranes. 365 31

The resolution of 96 polymethylmethacrylate intraocular lenses with convexo-plano optics, ranging in power from 13 to 27 diopters, was measured in air and water. The resolution of each lens was expressed in linear units of resolving power, which is the maximum number of line-pairs that can be resolved per millimeter, as described in the current ANSI Standard Z80.7-1984. There was no clearly defined relationship between linear resolving power measured in air and that measured in water. Measurements on high power lenses (greater than 20 diopters) indicate that it is possible for an intraocular lens to meet the current 100 line-pair per millimeter standard for resolution and still be a limiting factor in a patient's best attainable visual acuity. An alternative method for evaluating lens resolution is to determine the resolution efficiency (the relative percentage performance of a lens compared to a diffraction-limited lens of the same dioptric power). Using these units, a consistent and predictable relationship from air to water was demonstrated. Our findings confirm that if a minimum standard of 30% resolution efficiency in air is established, in contrast to linear resolving power, the lens will perform near its diffraction limit when implanted in the eye. For intraocular lenses of materials other than polymethylmethacrylate, a minimum resolution efficiency in air other than 30% may be required.
J Cataract Refract Surg 1987 Sep
PMID:Intraocular lens resolution in air and water. 366 32

The objective of this study was to determine the potential toxicity generated by the interaction of the Nd:YAG laser and Alcon IOGEL intraocular hydrogel lens material. The IOGEL lens is composed of poly 2-hydroxyethylmethacrylate, containing 38% water, previously shown to be highly biocompatible in a wide range of tissue culture and implantation experiments. In this study, intraocular lenses (IOLs) immersed in serum-free cell culture medium were purposely exposed to exaggerated doses of laser energy to cause extensive damage. An IOLAB polymethylmethacrylate (PMMA) lens served as a control lens material. The resultant solutions were assayed for cytotoxicity in a bioassay system using fourth passage human corneal endothelial cells. No cytotoxicity was seen in the bioassay for the IOGEL hydrogel IOLs or the PMMA control IOL at any laser range/dosage tested over a 72-hour incubation period. Hydrogel lenses exhibited decreasing yellowing with decreasing energy levels, and no lens discoloration was apparent at the lowest level of irradiation, 5 mJ/50 laser bursts; the PMMA control lens exhibited moderate yellowing at 15 mJ/50 bursts. Lens marking was moderate for all IOGEL IOLs; the PMMA lens marking was severe at the power level tested.
J Cataract Refract Surg 1987 Nov
PMID:Neodymium:YAG laser interaction with Alcon IOGEL hydrogel intraocular lenses: an in vitro toxicity assay. 368 86

There is good evidence that the non-enzymic chemical modification of proteins plays a role in the aetiology of cataract and diabetic sequelae. This paper presents new evidence that glycosylation of two major lens structural crystallins, alpha- and gamma-crystallins, by glucose 6-phosphate (G6P) induces conformational changes in the proteins. In addition the surface charge on the molecules is altered. These changes would affect protein-protein and protein-water interactions within the lens and could lead to disruption of the short-range order of the lens proteins which is essential for lens transparency. Conformational changes to lens proteins are known to occur in human cataractous lenses but their cause in vivo is not established. Cumulative chemical modification of proteins, over a period of decades, is a strong candidate as a causal agent.
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PMID:Conformational changes induced in lens alpha- and gamma-crystallins by modification with glucose 6-phosphate. Implications for cataract. 368 29

The effects of bendazac-L-lysine salt (bendazac-lysine) on some biochemical parameters (soluble and insoluble proteins, reduced glutathione, sulphydryl and disulphide groups, water content) in rabbit lens at different times after X-rays (2000 rads) were studied. The mature cataract (swelling and total lens opacity) developed 11-12 weeks after irradiation. In the mature cataract, the irradiated lenses not treated with bendazac-lysine (ILNTB) show a 32% increase in water content compared with controls; this increase is 12% in irradiated lens treated with bendazac-lysine (ILTB). Twelve weeks after irradiation the concentration of insoluble proteins in the controls, ILNTB and ILTB is 7.6%, 52.3% and 18.3% respectively. After 6, 8 and 12 weeks the concentration of reduced glutathione in ILNTB decreases by 23%, 81% and 92% as compared with the controls. In the ILTB the decrease is present only 8 and 12 weeks after X-irradiation and is of 55% and 69%, respectively. The sulphydryl-group content in the soluble proteins in ILNTB compared with the controls decreases by 26%, 38% and 47% after 6, 8 and 12 weeks, while in the ILTB a decrease is observed only after 8 and 12 weeks and is 6% and 12%, respectively. The decrease of the sulphydryl groups parallels the increase of the disulphide groups. This increase is already significant (P less than 0.01) after 6 weeks in the ILNTB, whereas it becomes significant in the ILTB only after 8 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of bendazac L-lysine salt on X-ray-induced cataract in the rabbit lens. 369 6


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