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Query: UMLS:C0086543 (cataract)
 29,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intracapsular cataracts obtained within 3 h after surgical extraction were photographed with the CCRG technique and immediately subjected to fluorescence spectroscopy followed by 31P- and 13C-nuclear magnetic resonance (NMR) spectroscopy. Fluorescence spectroscopy demonstrates an excellent correlation between nontryptophan fluorescence intensities and lens color. An interesting correlation was also observed between the degree of light scatter as determined by the 290-nm excitation peak for intrinsic lens tryptophan fluorescence and the CCRG (photographic) appearance of these cataractous lenses. Based on 100 cataracts analyzed, there is a strong correlation between this kind of light scattering measurement and the type and degree of lens opacification. A similar correlation is evident with the 31P-NMR organophosphate profiles in the lenses in which the sugar phosphate levels are elevated only in diabetic patients with cataracts ('diabetic cataracts'). Aside from fluorescence and 31P-NMR spectroscopy, selected lenses were also incubated with 5.5 nM 13C-glucose as soon as they were obtained, and the foregoing spectroscopy was performed, followed by 13C-NMR analyses to detect and monitor for sorbitol accumulation in young versus old normal lenses and in diabetic cataracts. These studies clearly demonstrate a direct correlation between nontryptophan-fluorescent chromophore levels, light scattering (determined by tryptophan excitation peaks), lens age and cataract type. In addition, the organophosphate profiles clearly delineate the diabetic cataracts, and the 13C-NMR spectra correlate well with the age-related decrease in aldose reductase activity.
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PMID:Photographic and spectroscopic correlations of human cataracts. 271 Apr 94

Metabolism in human senile cataracts has been studied using uniformly labeled [14C]glucose. Intracapsularly extracted lenses were cultured in TC-199 media with a glucose concentration of 5.5 mM. Results show that lactate production accounts for 97% of the glucose metabolized. Under these standard incubation conditions there is negligible accumulation of alpha-glycerol phosphate, glucose-6-phosphate, and sorbitol. The rate of lactate production was found to be relatively uniform over a range of cataract severities which were determined from the CCRG classification. The effects of several perturbants in the medium were measured. An ATP concentration of 3 mM was found to inhibit lactate production. Labeled glucose-6-phosphate in the medium was found to produce lactate at a rate approximately one half that of glucose. Elevated glucose concentration resulted in a slight decrease in lactate production and, in some lenses, production of a small amount of sorbitol. Overall, the glycolytic pathway appears to be functioning normally and without regard for cortical and nuclear opacification.
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PMID:Glucose metabolism by human cataracts in culture. 375 23

The validity and reproducibility with which six classifiers [one experienced (L.T.C.), and five novices (W.G., F.G., W.W., J.W. and O.W.)] used the CCRG cataract classification system was assessed. The validity of index classifications was assessed by computing sensitivities and pairwise interclass correlations between experienced and novice classifiers using the former's classification as the standard. The number of unordered combinations of terms in the CCRG's classification was reduced by combining cortical terms according to the CCRG's accepted system of staged simplification. The number of combinations of terms at each stage is as follows: Stage I (greater than 1000); II (127); III (63); IV (15); V (7); VI and VII (3) and VIII (2). Excellent agreement was obtained between the experienced and novice classifiers for Stages VII and VIII of the classification, good agreement for Stages V and VI and poor agreement for Stages IV, III and II (sensitivities of 97, 96, 72, 59, 40, 24 and 20% respectively). Good agreement was also achieved for the classifications of single lenticular regions, except for subcapsular regions. The intra- and interobserver reproducibility was assessed by computing the Kappa statistic to (1) compare classifications between novice observers and (2) compare repeat classifications made by the same observer by viewing the same cataract once on each of three different days. The novice classifiers had excellent intraobserver reproducibility for Stages VII and VIII (Kappas of 0.87 and 0.97 respectively), good reproducibility for Stages IV, V and VI (Kappas of 0.53, 0.62 and 0.62, respectively) and marginal reproducibility for stages II and III (Kappas of 0.39 and 0.40, respectively). The intraobserver reproducibility of the experienced classifier was superior to the others for virtually all characteristics with excellent reproducibility for Stages IV, V, VI, VII and VIII with Kappas of 0.79, 0.90, 1.0, 1.0 and 1.0, respectively and good reproducibility for Stages II and III (Kappas of 0.55 and 0.64, respectively). These results indicate that the simplified CCRG cataract classification system (Stages IV-VIII) passes the minimum standards for reproducibility. The performance of the experienced classifier far exceeds the minimum standards and indicates the feasibility of improving classifier performance with training and practice.
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PMID:Validity and reproducibility of the Cooperative Cataract Research Group (CCRG) cataract classification system. 397 55

From studies involving 31 cataracts classified by the CCRG system and eight normal human lenses, it has been found that the adult human lens contains an enzyme system capable of oxidizing 1-2 mumol of glyceraldehyde, acetaldehyde, propionaldehyde, formaldehyde, and malonaldialdehyde per hour to their carboxylic acid form. Roughly 30 mumol G-3-P can be oxidized per hour. Statistically, the level of the oxidase system in nuclear cataracts and deeply pigmented lenses was found to be the same as for normal lenses. The deficiency of an enzyme responsible for the oxidation of highly reactive aldehydes thus seems unlikely to be involved in nuclear cataract formation and the browning of the lens. Evidence that the observed oxidase activity occurs via two separate enzymes: aldehyde dehydrogenase and glyceraldehyde-3-P dehydrogenase was achieved by studying the response of enzyme to substrate and activators (dithiothreitol and arsenate) and by final separation of enzyme activities. Differences in pH optima and heat treatment response further distinguished one enzyme from the other.
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PMID:Aldehyde metabolism in the human lens. 661 79

The effects of several media and temperatures on the features (i.e. classification) of human cataracts have been studied with the aim of defining those storage conditions that least alter the appearance of the cataract after extraction. It was found that distilled water, normal saline, TC 199 medium with extra bicarbonate and 5.5 mM glucose, and silicone oil at 4 degrees, 36 degrees, and 37 degrees C are all unsatisfactory for preserving cataracts for more than 1 hr. Normal saline and TC 199 medium with bicarbonate and glucose are satisfactory for period not exceeding 30 to 60 min at 4 degrees C. The best set of conditions, one that leads to no significant change in the appearance of the cataract, is storage in a small covered glass vial at 4 degrees C with no added fluid. In this moist chamber, no significant changes in cataract classification occurred during a 4 hr period. The effect of -20 degrees C for 15 min on the appearance of a nuclear cataract was negligible, and it was concluded that lenses so treated could be used for a correlation between the nuclear cataract's CCRG classification and its light scattering properties, as studied in Parts II and III.
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PMID:Studies on human cataracts. I. Evaluation of techniques of human cataract preservation after extraction. 720 78

Human lens nuclei were collected during routine cataract surgery and used to study the role of oxidation in cataract formation and brunescence. This study focused on the comparison of the intensities of nuclear opacity and pigmentation (brunescence) with the changes in free glutathione (GSH) and the three species of protein-thiol mixed disulfides: protein-S-S-glutathione (PSSG), protein-S S-cysteine (PSSC) and protein-S-S-gamma-glutamylcysteine (PSSGC). Eighty-one freshly excised human lens nuclei from a population with a mean age of 77 were used. The nuclear color was graded using the CCRG system, ranging from yellow to dark brown. The nuclear cataract opalescence of these lenses was also graded using the LOCS II system, ranging from LOCS II NO-1 to NO-4. Three normal human lenses (average age of 88 yr) were also included in the study as controls. The nuclear samples were each analyzed for free GSH and protein-thiol mixed disulfides, respectively. It was found that nuclear GSH decreased as the nuclear color increased from yellow to dark brown (from 0.73+/-0.13 to 0.13+/-0.03 micromole g wet wt-1) and as the nuclear opalescence increased from NO.1 to NO.4 (from 0. 80+/-0.19 to 0.20+/-0.01 micromole g wet wt-1). All these values were lower than that of GSH in normal controls (1.43+/-0.59 micromole g wet wt-1). Levels of both PSSG and PSSC progressively increased, however, as the nuclear color intensified. PSSG increased from 0.29+/-0.05 to 0.91+/-0.11 micromole g wet wt-1while PSSC increased from 0.13+/-0.04 to 0.41+/- 0.06 micromole g wet wt-1. PSSGC concentration progressively increased with increases in both nuclear pigmentation (from 0.05+/-0.01 to 0.23+/-0.05 micromole g wet wt-1) and nuclear opacity (from 0.02+/-0.00 to 0.20+/-0.02 micromole g wet wt-1). In comparison, normal controls had lower levels of all three mixed disulfide species: PSSG, 0.22+/-0.06; PSSC, 0.08+/-0.02; PSSGC, 0.02+/-0.06 micromole g wet wt-1, respectively. The correlation of lens nuclear color and opalescence intensity with nuclear protein S-thiolation indicates that protein-thiol mixed disulfides may play an important role in cataractogenesis and development of brunescence in human lenses.
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PMID:Correlation of nuclear color and opalescence with protein S-thiolation in human lenses. 1032 68