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

Gel filtration of water-soluble protein shows a substantial increase in HM+ alpha-crystallin and a marked decrease in beta- and gamma-crystallins in cortical cataract. A decrease in beta 1-crystallin in cortical punctate opaque lenses is also striking. In nuclear cataractous lenses HM+ alpha- and beta-crystallin increase, while gamma-crystallin decreases. The urea-soluble protein from clear lenses contains mainly of alpha beta chain, whereas in cataractous lenses the relative amounts of the 28 and 23ku polypeptides (the components of beta-crystallin) increased markedly. In cataractous lenses the relative amount of membrane intrinsic proteins decreases slightly and it has little statistical meaning.
 ...
PMID:[Changes in water-soluble, urea-soluble and membrane intrinsic proteins in human senile cataract]. 784 96

The occurrence of age-related cataract associated with a persistent hyaloid vascular system is the most prominent feature in SAMP9, an inbred strain of Senescence-accelerated Mouse. To examine the cataractogenesis, we analysed protein changes in the process of cataract formation in the lens. The cataractous lenses showed a striking decrease in water-soluble protein content, in contrast to increases in the amount of water insoluble protein. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blots of water-soluble protein in the cataractous lenses showed additional high molecular weight beta-crystallin proteins of about 43 kDa, concomitant with decreased amounts of 29-kDa and 31-kDa beta-crystallins and 21-kDa gamma-crystallin, as compared with findings in normal lenses. Although there was no apparent difference between the patterns of SDS-PAGE of urea-soluble and urea-insoluble proteins isolated from cataractous and normal lenses, slightly increased reactivity of bands around 43 kDa against anti-beta-crystallin antibody was observed in cataractous lenses. The calcium content was elevated and activity of transglutaminase was increased in the cataractous lenses. While the molecular weight of beta-crystallin polymers cross-linked in vitro by exogenous transglutaminase was not completely compatible with those of high molecular weight beta-crystallins observed in the cataractous lenses, these findings do suggest the contribution of this enzyme to production of high molecular weight beta-crystallins and to insolubilization of these proteins in the cataractous lenses in SAMP9.
 ...
PMID:Protein alterations in age-related cataract associated with a persistent hyaloid vascular system in senescence-accelerated mouse (SAM). 785 22

The total proteins, water--soluble proteins and the urea--soluble proteins of the lens from fetal, adult and senile cataract were determined by SDS--PAGE. It was found that there was a 43KD polypeptide in the capsular--epithelium of all lens stated above. The band on SDS-PAGE corresponding to 43KD polypeptide was wide in the water--soluble proteins of the cortex and nucleus of the lenses obtained from over 14-year-old individuals. It became blurred in the urea--soluble proteins of cortex and nucleus of lens with aging, whereas it became almost disappeared in the senile cataract lens.
 ...
PMID:[The 43KD polypeptide in the proteins of human lens]. 795 52

High resolution calorimetry and spectral measurements have been employed to examine folding/unfolding behaviour of gamma-crystallins which are known to contain two homologous domains. Results have been analyzed in terms of selective unfolding of domains, interdomain interactions, conformational stability and the existence of intermediates in the order-disorder transition equilibrium. Both spectral and thermotropic data indicate that, in terms of structural hierarchy, these proteins can be divided into two distinct groups, gamma II and gamma IIIB belonging to one and gamma IIIA and gamma IVA to the other. The unfolding/folding characteristics of these two groups are distinctly different. Equilibrium unfolding of gamma II and gamma IIIB is biphasic indicating the existence of an intermediate in which one domain unfolds and the other remains in the native form. The absence of a cooperative transition in gamma IIIA and gamma IVA in acidic urea has also been attributed to a structured intermediate, most likely a molten globule, which may not be thermodynamically as distinct as of the former group. The difference in the equilibrium folding/unfolding transition of these two groups has been explained by subtle differences in the packing arrangement of their two domains and interactions between them. Since the intermediates, under certain circumstances, are known to aggregate, they are likely to play a critical role in the etiology of human cataract formation.
 ...
PMID:Differential domain folding/unfolding of gamma-crystallins: existence of two distinct groups. 800 19

Restriction of dietary calorie intake is associated with life extension and with the delay of age-related disorders. Preliminary studies demonstrated that by feeding the Emory mouse a diet restricted by 21% in calories cataract and insolubilization of protein could also be delayed. To observe the effects of calorie restriction over prolonged portions of adulthood, Emory mice were fed the control diet (C) or a diet restricted by 40% in calories (R). Feeding the R diet was associated with delayed formation or progress of cataract over virtually the entire second half of life. At 11 months of age, bilateral grade 5 cataracts were present in 17% and 2% of C and R lenses, respectively. At 22 months of age, bilateral grade 5 cataracts were present in 90% and 18% of C and R lenses, respectively. The distribution of alpha-, beta-, and gamma- crystallins in the water-soluble, urea-soluble, and SDS-soluble fractions indicates more similarities than differences between C and R lenses with a specific grade of cataract or of a given age. However, there were significant and abrupt (after grade 4 cataract) losses of particular gamma-crystallins; gamma-crystallins which were not prominent at earlier stages became the major gamma-crystallin moieties. Losses of alpha-crystallins were also noted upon cataract formation or aging in most of the fractions. Aggregates including gamma- and alpha-crystallins also accumulate faster in the C group.
 ...
PMID:Cataract incidence and analysis of lens crystallins in the water-, urea- and SDS-soluble fractions of Emory mice fed a diet restricted by 40% in calories. 813 32

Using a modified enzyme-linked immunosorbent assay that included dissociation of antigen antibody complexes with 6M urea solution, we analyzed the avidity of Toxoplasma-specific IgG in aqueous humor and serum samples from 24 patients with toxoplasmic chorioretinitis. As a control, we studied aqueous humor and serum samples from 14 cataract patients without history of uveitis and serum samples from 10 patients with recent primary systemic toxoplasmic infection without ocular lesions. IgG avidity was markedly lower in aqueous humor samples from patients with toxoplasmic chorioretinitis than in serum samples, despite those samples presenting higher levels of Toxoplasma-specific IgG than in serum samples. The detection of the low-avidity Toxoplasma-specific antibodies can offer a valuable aid to make a specific etiologic diagnosis and perhaps contribute to understand the pathogenic mechanisms of ocular toxoplasmosis.
 ...
PMID:Analysis of aqueous humor in ocular toxoplasmosis: detection of low avidity IgG specific to Toxoplasma gondii. 817 80

The author assessed the physiological aging parameters of 38 apparently healthy subjects who were over 80 years old 1989, who were not on medication, and who had consulted with the Keio Health Counseling Center over 10 years. All subjects had no history of overt vascular disease and/or malignancy in 1989. In 17 of 38 subjects, physical, hematological and blood chemical parameters when they were in their 70s were analyzed. Many parameters were unchanged and remained within normal limits for ordinary adults. Cataract, atherosclerotic change of optic fundi and diagonal ear lobe creases were seen in all subjects during the study period. Concerning standard deviations, those of forced expiratory volume in one second/predicted vital capacity and pure tone average (acoustic ability) decreased with age, unlike those of other parameters. Furthermore, multiple regression analysis, revealed that serum albumin decreased but pure tone average, Scheie's atherosclerotic score, senile cataract, HDL-cholesterol blood urea nitrogen and forced expiratory volume in one second/predicted vital capacity increased with age. This study was not cohort study with selected subjects but shows very slight change of almost any parameter irrespective of age and abnormality can suggest the existence of disease.
 ...
PMID:[The changes in physico-chemical parameters obtained from apparently healthy aged people followed over ten years]. 823 Jul 84

Oxidative stress has long been speculated to play an important role in cataractogenesis. In the H2O2-induced cataract model, rat lens showed extensive biochemical damage but very mild morphological changes after being exposed to H2O2 (0.5 mM) for 24 hr in culture. This damage included reduced glutathione (GSH) depletion, protein-GSH mixed disulfide (PSSG) elevation but not protein-protein disulfide (PSSP) formation. In order to understand the role of protein-thiol mixed disulfide formation in relation to the sequence of events during cataract induction, we conducted a long term H2O2 exposure study for up to 96 hr to monitor the dynamic changes in GSH and PSSG levels, the formation of PSSP aggregate, protein solubility, and the progression in lens opacity. Rat lenses were cultured in 0.5 mM H2O2 and harvested at intervals of 24, 48, 72 and 96 hr for the examination of morphological and biochemical changes. Contralateral lenses cultured in H2O2-free media were used as controls. It was found that the lenses had only patchy opacity at the equator after 24 hr, but became hydrated suddenly at 48 hr (31% heavier than the control), with an opacity which involved the entire outer cortical region. By 72 hr incubation, the nucleus was opacified. Lens GSH progressively decreased with time of H2O2 exposure, 40% was lost by 24 hr and over 95% by 48 hr. There was a concomitant elevation of PSSG, 16-fold over the controls by 24 hr and 45-fold by 48 hr followed by a decline to 34-fold after 72 hr. In addition, the level of protein-cysteine mixed disulfide (PSSC) was elevated after 48 hr incubation in H2O2. At this time point, PSSP aggregates began to appear both in water soluble (WS) and urea soluble (US) fractions along with a drastic reduction in protein solubility. Western blot analysis of the protein fractions identified beta and gamma, but not alpha-crystallin in the disulfide-containing aggregates. The lens clarity and biochemical changes partially recovered if the oxidant was removed within 24 hr, indicating a potential therapeutic role for antioxidants. The complete normalization of PSSG level under this recovery condition signifies that cells may have a natural defense system for controlling PSSG elevation.
 ...
PMID:The effect and recovery of long-term H2O2 exposure on lens morphology and biochemistry. 840 82

Uremia has been implicated in cataractogenesis due to protein carbamylation by cyanate derived from urea. The present study was designed to directly identify the effects of carbamylation on actin polymerization and the possible contribution to cataract formation. The susceptibility of actin to carbamylation is expected because of the 19 lysines distributed along its length. The lysines of actin were selectively carbamylated by methylisocyanate (MIC) at pH 8.0 and 4 degrees C and actin polymerization assayed by high-shear viscometry, fluorescence and transmission electron microscopy. Our results provide evidence that non-enzymatic carbamylation of the lysine residues prevents the polymerization of actin. In addition, this carbamylated actin inhibited the polymerization of nascent, unmodified actin. High-shear viscosity measurements demonstrated decreased initial apparent rates and decreased steady-states (final specific viscosities) of polymerization. Fluorescence measurements showed decreased relative intensities of fluorescence versus control and confirmed the inhibitory effects of carbamylation by MIC on the steady state of F-actin. Transmission electron microscopy (TEM) showed the presence of disorganized filaments when carbamylated actin was added to polymerizing unmodified actin. Our results suggest that carbamylation of actin can cause a loss of ordered filament structure and shape of the lens fiber cell, thus predisposing it to cataract development.
 ...
PMID:Methylisocyanate and actin polymerization: the in vitro effects of carbamylation. 844 78

Studies have been conducted to assess the possible preventive effect of pyruvate against lens protein oxidation and consequent denaturation and insolubilization. Rat lens organ culture system was used for these studies. The content of water insoluble proteins (urea soluble) increased if the lenses were cultured in medium containing hydrogen peroxide. Incorporation of pyruvate in the medium prevented such insolubilization. The insolubilization was associated primarily with loss of gamma crystallin fraction of the soluble proteins. PAGE analysis demonstrated that insolubilization is related to -S-S- bond formation which was preventable by pyruvate. Since pyruvate is a normal tissue metabolite the findings are considered pathophysiologically significant against cataract formation. This was apparent by the prevention of selenite cataract in vivo by intraperitoneal administration of pyruvate.
 ...
PMID:Prevention of oxidative damage to rat lens by pyruvate in vitro: possible attenuation in vivo. 852 99


<< Previous 1 2 3 4 5 6 7 8 Next >>