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)

Plasma membrane with its associated extrinsic proteins was isolated from normal and cataractous rat lenses by centrifugation of the total water insoluble fraction from homogenized lenses on a discontinuous sucrose gradient. Membrane, which we call "native" membrane, was recovered mainly from the 25/45% sucrose interface. Development of the experimental U18666A cataract resulted in plasma membrane shifting to higher density (the 50/55% sucrose fraction) and great increases in the urea soluble protein content of the lens. At early stages of cataract development, most of the increased urea soluble protein was membrane associated, presumably as extrinsic protein. With advancing cataract, most of the urea soluble protein appeared in an essentially membrane-free pellet fraction. The urea soluble protein associated with the cataract membrane was shown by combined IEF, SDS-PAGE, Western blotting, amino acid compositional analysis and protein sequence determinations to be mainly composed of modified alpha- and beta-crystallins. Alpha A-crystallin truncated by not more than 27 residues from the carboxyl terminus plus beta b1 crystallin truncated by 49 residues from the amino terminus were conclusively identified. In addition to beta b1, a population of six alpha-crystallin derived polypeptides were specifically enriched in the cataract membrane fraction. Four of these six alpha-crystallins appear to be truncated from their carboxyl terminus, a modification which should have increased their hydrophobicity. The pellet fraction, which accumulated in the lens nucleus as the cataract advanced, was enriched in urea soluble gamma-crystallin derived polypeptides. We suggest that protein insolubilization in this experimental cataract involves the selective and tight association of principally modified alpha-crystallins to the fiber cell plasma membrane.
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PMID:Selective association of crystallins with lens 'native' membrane during dynamic cataractogenesis. 142 24

Urea-soluble and intrinsic membrane proteins from normal and galactose cataractous rat lenses were analyzed by SDS-PAGE. During cataract formation, MP22 increased whereas MP26 decreased almost to nil and MP24 emerged. However, the relative amount of MP18 remained essentially unchanged. These results suggested a conversion of MP26 to MP22 during cataract formation. We also observed the changes in the relative abundance of the polypeptides of the urea-soluble fraction with cataractogenesis.
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PMID:Changes of urea-soluble and intrinsic membrane proteins in rat lenses during the formation of galactose cataract. 147 76

Studies were carried out comparing the ability of urea extraction and sonication to solubilize the water-insoluble (WI) protein fraction from human lens tissue. Sonication and urea extraction were able to solubilize greater than 80% of the insoluble protein whether whole lenses or lens nuclei were used. This was true for normal lens and +1 cataracts; however, only 60% solubilization was obtained with the WI fraction from more advanced cataracts. Equal aliquots of a WI fraction from both pooled normal and pooled cataract lens nuclei were solubilized with and without reducing agents. The addition of dithiothreitol (DTT) had no significant effect on solubilization of the normal lens WI fraction. DTT did increase the protein solubilized from the cataract WI fraction by 30% with urea extraction; however, no increase was seen with sonication. When sodium borohydride was used as the reducing agent, essentially the same results were obtained. The solubilized protein populations were identical by SDS-PAGE and amino acid analysis. The addition of reducing agents had no effect on the amino acid content of the solubilized proteins with the single exception of lysine. This amino acid was markedly decreased in the proteins extracted in the presence of 40 mM sodium borohydride, but not with DTT. These data suggest that the borohydride not only increased the amount of protein solubilized, but likely also stabilized glycated lysine residues during the acid hydrolysis. Therefore, sonication readily provides a soluble preparation of the WI proteins from normal and cataract lens nuclei without the need for denaturing agents, however, disulfide-linked and lysine modified crystallins were best solubilized with urea.
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PMID:Studies on the solubilization of the water-insoluble fraction from human lens and cataract. 148 36

In the past, almost all studies on naphthalene cataract were based on in vivo experiments. Such studies are laborious and time-consuming and are complicated by systemic toxicity arising from the metabolites of naphthalene. In order to study the direct effects of naphthalene metabolites on the lens, we established an in vitro 'naphthalene cataract' model system by exposing rat lens to naphthalene dihydrodiol (2.5 x 10(5) M) containing medium for 48 hr. Under these conditions, we analysed several biochemical parameters including the glutathione level, protein mixed disulfides, protein patterns on SDS-gels, active transport, NA+/K(+)-ATPase activities and the measurement of naphthalene metabolites in the cultured lenses. The results showed that both the morphological and biochemical changes were very similar to those observed in lenses of rats fed naphthalene (1 g kg-1 day-1). Furthermore, ALO1576 completely blocked the in vitro changes as it did in vivo. Therefore, this model system can be used as a new tool to investigate the mechanism of naphthalene cataract formation. Other naphthalene metabolites such as 1-naphthol, 2-naphthol, 1,2-dihydroxynaphthalene and 1,2-naphthoquinone were also studied in vitro and the results showed that the effects of these naphthalene metabolites were very different from those observed in naphthalene cataracts in vivo.
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PMID:Establishment of a naphthalene cataract model in vitro. 154 43

Exposure of cultured rabbit lens epithelial cells to repetitive doses of UV-B radiation delays their growth and alters the synthesis of specific proteins. Irradiated cells on the shoulder of the survival curve exhibited a dose-dependent decrease in growth when subcultured in serum-supplemented medium. UV-B irradiation did not affect the subsequent attachment efficiency of the cells. Control and UV-B irradiated cells were incubated with [35S]methionine and the pattern of protein synthesis in the cells was analyzed by SDS-PAGE and autoradiography. Analysis of the labeled proteins from cells exposed to UV-B radiation showed the induction of a 32 kD polypeptide and the loss of a 26 kD polypeptide compared with controls. Analysis of the proteins released by the UV-B irradiated cells into the culture medium revealed the 50% loss of a 37 kD radiolabeled protein compared with controls. The alteration of protein synthesis in lens epithelial cells by UV-B radiation may contribute to cataract formation.
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PMID:Effect of ultraviolet-B radiation on protein synthesis in cultured lens epithelial cells. 209 21

Purified lens fiber membrane fractions from Emory mouse lenses and cataract-resistant control lenses were compared by SDS-PAGE. The differences in polypeptide patterns were determined for three ages. There was a striking alteration in MP24/MP26 ratio during aging and cataractogenesis which appears to be due to a normal age-dependent conversion of MP26 to MP24, and which is accelerated during cataractogenesis.
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PMID:Alterations of urea-insoluble membrane fraction, MP26, of Emory mouse lenses in aging and cataractogenesis. 234 82

Aqueous humor from 23 patients with Fuchs' heterochromic cyclitis (FHC) was analysed by a number of immunological methods. Intraocular IgG synthesis was found in 65% of patients and oligoclonal IgG bands, mainly of the IgG1 subclass, identified in 57%. There was a relative increase in IgG1 (P less than 0.01) as compared to patients with senile cataract. Local production of the cytokine Interleukin-6 was demonstrated in 63% of patients (P less than 0.01). Analysis of aqueous by HPLC and SDS-PAGE failed to reveal any abnormalities specific for FHC. These findings add further evidence to the theory of immune dysregulation in this condition.
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PMID:Aqueous humour analysis in Fuchs' heterochromic cyclitis. 238 14

We analyzed the protein composition of human aqueous humor. Samples were obtained by paracentesis from 25 human eyes (age range 64-92 years) at elective cataract surgery, and from 20 age-matched post-mortem eyes within 1.5 to 18 hr after death. Individual samples were assayed for total protein, and the polypeptides were separated by qualitative SDS-PAGE into high-, medium- and low-molecular-weight ranges and then silver-stained. The clinical samples showed a remarkable consistency in the total protein values (mean +/- SEM: 12.4 +/- 2.0 mg per 100 ml) and no detectable variations in the profiles of the silver-stained proteins. Twelve major protein fractions, with apparent molecular weights of 140, 80 (doublet), 67, 60 (doublet), 35, 27, 25, 17, 14.6 and 9 kDa, were present. A preliminary analysis showed that the 17 kDa band contained a molecule resembling basic fibroblast growth factor. Two additional samples of aqueous humor from patients whose blood/aqueous barrier was compromised during paracentesis showed a quantitative and qualitative increase in the polypeptides that were present. Compared with the samples of aqueous humor obtained at surgery, the post-mortem samples exhibited a greater variability in total protein content (56.1 +/- 11.6 mg per 100 ml) and an increased number of high- and low-molecular-weight protein fractions. In view of wide differences in the clinical parameters, including ocular and systemic medications, systemic illness, surgical premedications, anesthesia and total serum protein values, the similarity in the protein profiles of the carefully drawn surgical samples is most remarkable. Our results indicate that, in patients who underwent elective cataract surgery, the levels of major proteins in human aqueous humor are not affected by wide individual variations in the clinical parameters. We attribute this finding to the care taken in the collection of aqueous humor samples.
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PMID:Protein composition of human aqueous humor: SDS-PAGE analysis of surgical and post-mortem samples. 292 Jul 79

Antisera against synthetic peptides corresponding to various regions of the Main Intrinsic Polypeptide (MIP26K) of fiber lens membranes have been used to probe Western blots of Emory mouse lens proteins resolved by SDS-polyacrylamide gel electrophresis. When compared with clear lenses from control animals of approximately the same age, the MIP26K component from Emory mouse lenses demonstrated no quantitative changes in the binding of anti-MIP26K256-263 and anti-MIP26Kwhole sera. In contrast, the MIP26K component from Emory mouse lenses bound significantly better to two other antisera directly against other parts of the molecule (antiMIP26K229-237 and anti-MIP26K252-259). Furthermore, this increase in binding was approximately proportional to the degree of lens opacification. Together, these results demonstrate that during the opacification process of the Emory mouse lens, there occur covalent changes in the MIP26K molecule that, in part, may mimic those occurring in the human senile cataract.
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PMID:Changes in the major intrinsic polypeptide (MIP26K) during opacification of the Emory mouse lens. 304 12

Investigations were carried out to clarify the role of autoimmune phenomena in the pathogenesis of cataract in the adult human lens. Studies were carried out to determine the presence of serum antibodies to lens protein in patients with senile cataract, in patients with diabetes mellitus with and without cataract, and in healthy adult controls using the interfacial test and the gel-diffusion technique. Non-specific antibodies were removed by adsorption of sera with homogenized rat liver. A high proportion of healthy adults was found to have anti-lens protein antibodies (44.4% by the gel-diffusion method). In contrast, patients with cataract and diabetic patients with no cataract demonstrated double this incidence (82% and 80%), while all diabetic patients with cataract showed the presence of antibodies (P = 0.0002). The possible causes for the development of lens antibodies in normal healthy humans are discussed. Also, the causes for the higher incidence of lens antibodies in patients with cataract and in diabetic subjects with no clinical evidence of cataract are considered in relation to cataract formation. Homogenates of cataractous lenses when investigated revealed the presence of both IgG and IgM immunoglobulins, the former probably to a greater extent. Fluorescent microscopy on cryosections of senile and diabetic cataractous lenses revealed the presence of immunoglobulins within the lens. The antigen in the immune complexes isolated from homogenized cataractous lenses was characterized by the SDS-polyacrylamide gel electrophoresis method. A single band was consistently obtained and the molecular weight of the protein was estimated to be between 35,000 and 40,000. The strong possibility of auto-antibodies to lens protein being of aetiological significance in the pathogenesis of cataract is discussed.
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PMID:The role of autoimmune phenomena in the pathogenesis of cataract. 311 83


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