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)

The mydriasis provocative test with 1% cyclopentolate (CPT) was performed on 218 patients with suspected or untreated open-angle glaucoma, on 431 eyes in all. Significant IOP elevations (larger than or equal to 8 mmHg) were demonstrated in 21 eyes of 18 patients. The present paper analyses the responder group and presents some other investigation results and clinical findings to throw additional light on the mechanism of IOP elevation in responders. The responders did not differ from the other patients of the material in age or sex. Patients with capsular glaucoma constituted the biggest group among the responders. 48% of the significant IOP elevations during CPT were encountered in eyes with pseudoexfoliation (PE) and open-angle glaucoma. A positive response during CPT was statistically significantly more common in PE eyes than in eyes without PE. Capsular glaucoma was diagnosed immediately or later in all PE eyes which displayed a larger than or equal to 5 mmHg IOP elevation during the CPT. In addition to the importance of pigment in PE eyes, PE material may play a certain role in the elevation of IOP . The mechanism of this role is not known. No correlation was established between the results of the water drinking test and the CPT. The mechanism that causes the elevation of IOP must be quite different in these two tests. Nor was a statistically significant difference observed in the incidence of cataract, the maximal variation of IOP in the 48-h tension curve, the occurrence of cupping of the optic disc or visual field defects between the responder and non-responder eyes in the glaucomatous group.
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PMID:The cyclopentolate provocative test in suspected or untreated open-angle glaucoma. II. Clinical studies on the mechanism of intraocular pressure elevations. 98 41

Using the technique of optical mixing spectroscopy, we have observed the Brownian movement and measured the diffusivity of proteins within whole, intact human and bovine lenses. The magnitude and the temperature dependence of the protein diffusivity in bovine and normal human lenses implies that cold cataract is the result of a first-order phase separation of the protein-water mixture in the lens. The magnitude of the diffusivity of proteins within cataractous human lenses indicates the presence of large aggregates of proteins.
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PMID:Observation of protein diffusivity in intact human and bovine lenses with application to cataract. 113 41

The vertebrate eye lens is a solid cyst of cells which grows throughout life by addition of new cells at the surface. The older cells, buried by the newer generations, differentiate into long, prismatic fibers, losing their cellular organelles and filling their cytoplasms with high concentrations of soluble proteins, the crystallins. The long-lived lens fibers are interconnected by gap junctions, both with themselves and with an anterior layer of simple cuboidal epithelial cells at the lens surface. This network of gap junctions joins the lens cells into a syncytium with respect to small molecules, permitting metabolic co-operation: intercellular diffusion of ions, metabolites, and water. In contact with nutrients at the lens surface, the epithelial cells retain their cellular organelles, and are able to provide the metabolic energy to maintain correct ion and metabolite concentrations within the lens fiber cytoplasms, such that the crystallins remain in solution and do not aggregate (cataract). Gap junctions are formed by a family of integral membrane channel-forming proteins called connexins. Gap junctions between lens epithelial cells are composed of a connexin which is common between many different cell types, notably myocardial cells and connective tissue fibroblasts. The gap junctions between epithelial cells and lens fibers have not yet been biochemically characterized. The gap junctions formed between lens fibers are composed of at least two different connexins, one of which has not been detected between other cell types. The unusual physiology and longevity of the lens fibers may require the special set of connexins which are found joining these cells.
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PMID:The crystalline lens. A system networked by gap junctional intercellular communication. 132 Apr 31

Kasturba Hospital in Sevagram, India, has helped to initiate an outreach health program for nearby villages. A health insurance scheme has evolved where the community contributes sorghum for a fund and participates in decision-making and the supervision of village health workers. Contributors are entitled to free primary care and subsidized referral care. Only villages where at least 75% of the poor community agreed to enroll in the health insurance scheme were adopted by the hospital. The hospital offers insured persons free inpatient treatment for unexpected illness and a 75% subsidy for care during normal pregnancy or with cataract and hernia operations. The mobile health team, comprising auxiliary nurse-midwife, social worker, and village health worker, provides maternal and child health services in the localities. The village health workers provide symptomatic drug treatment, exercise a preventive role with the help of visiting health team members, and refer patients to hospital. The auxiliary nurse-midwife and social workers organize visits for vaccination and provide maternal and child health care. The doctor in charge treats patients in the hospital and trains village health workers. More than 75% of the villages in the area have enrolled in the scheme over the last 10 years. No vaccine-preventable illness (measles, poliomyelitis, diphtheria, whooping cough, tetanus) was reported in children or mothers after mass immunization was instituted, no maternal deaths have occurred during the past 10 years, and perinatal mortality has fallen steeply. The village health teams are now regarded as counselors on health-related matters, among them drinking-water supplies, irrigation, and programs for income generation. It is necessary to regulate the private health sector, including professionals, the drug industry, and investors. If outpatient services are opened up to the private sector, a system of universal medical insurance, financed by local government, should operate.
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PMID:Risk-sharing in rural health care. 141 30

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

Looped intraocular lenses (IOLs) fixate by exerting centripetal pressure on the ocular tissues. The ability of the flexible loops to maintain pressure depends on their rigidity (i.e., resistance to flexion) and their "memory" (i.e., ability to restore original configuration after a long period of compression). We studied the memory of 30 different posterior chamber IOLs, with loops made of polypropylene (PP) and poly(methyl methacrylate) (PMMA), of various diameters, styles, and designs. The lenses were inserted into plastic wells, 9.5 mm in diameter, and immersed in water (37 degrees C) for one month. They were then placed on an open plate and allowed to re-expand for one month. Loop memory was calculated as the difference in diameter between the initial (pretest) measurement and measurements taken during the compression and release periods. The results showed that short (12.0 to 12.5 mm) IOLs had relatively better memory than longer (13.5 to 14.0 mm) IOLs. Those with PP loops expanded more and for longer periods than those comparable size and design with PMMA loops. One-piece, all-PMMA lenses exhibited the best loop memory. These lenses have the high rigidity of the PMMA material and the good memory of the design. Thus, the total IOL diameter can be reduced to 12.0 mm while providing long-term constant pressure on the capsular bag to maintain stable fixation.
J Cataract Refract Surg 1992 Nov
PMID:Loop memory of posterior chamber intraocular lenses of various sizes, designs, and loop materials. 143 62

Poly(methyl methacrylate) (PMMA) based intraocular lenses (IOLs) such as injection-molded PMMA and lathe-cut PMMA IOLs and soft IOLs such as silicone and poly(hydroxyethyl methacrylate)(polyHEMA) IOLs were tested for vulnerability to Nd:YAG laser photodisruption. The laser beam was focused on the posterior surface and inside of the IOLs in balanced salt solution. Cracks and central defects with radiating fractures were observed in PMMA IOLs; blistered lesions and localized pits were observed in silicone and polyHEMA IOLs, respectively. A molten edge surrounding the large hole, which was an indication of the thermal effect of the laser, was observed in the injection-molded PMMA while only a minute lesion was found in the polyHEMA IOL which contained 38% water. The size of the superficial damage of the IOL increased as the power of laser irradiation increased and PMMA IOLs showed greater damage than soft IOLs (P < .05).
J Cataract Refract Surg 1992 Nov
PMID:Effect of neodymium:YAG laser photodisruption on intraocular lenses in vitro. 143 66

Tocopherols and tocotrienols (vitamin E) and ascorbic acid (vitamin C) as well as the carotenoids react with free radicals, notably peroxyl radicals, and with singlet molecular oxygen (1O2), this being the basis of their function as antioxidants. RRR-alpha-tocopherol is the major peroxyl radical scavenger in biological lipid phases such as membranes or low-density lipoproteins (LDL). L-Ascorbate is present in aqueous compartments (e.g. cytosol, plasma, and other body fluids) and can reduce the tocopheroxyl radical; it also has a number of metabolically important cofactor functions in enzyme reactions, notably hydroxylations. Upon oxidation, these micronutrients need to be regenerated in the biological setting, hence the need for further coupling to nonradical reducing systems such as glutathione/glutathione disulfide, dihydrolipoate/lipoate, or NADPH/NADP+ and NADH/NAD+. Carotenoids, notably beta-carotene and lycopene as well as oxycarotenoids (e.g. zeaxanthin and lutein), exert antioxidant functions in lipid phases by free-radical or 1O2 quenching. There are pronounced differences in tissue carotenoid patterns, extending also to the distribution between the all-trans and various cis isomers of the respective carotenoids. Antioxidant functions are associated with lowering DNA damage, malignant transformation, and other parameters of cell damage in vitro as well as epidemiologically with lowered incidence of certain types of cancer and degenerative diseases, such as ischemic heart disease and cataract. They are of importance in the process of aging. Reactive oxygen species occur in tissues and cells and can damage DNA, proteins, carbohydrates, and lipids. These potentially deleterious reactions are controlled in part by antioxidants that eliminate prooxidants and scavenge free radicals. Their ability as antioxidants to quench radicals and 1O2 may explain some anticancer properties of the carotenoids independent of their provitamin A activity, but other functions may play a role as well. Tocopherols are the most abundant and efficient scavengers of peroxyl radicals in biological membranes. The water-soluble antioxidant vitamin C can reduce tocopheroxyl radicals directly or indirectly and thus support the antioxidant activity of vitamin E; such functions can be performed also by other appropriate reducing compounds such as glutathione (GSH) or dihydrolipoate. The biological efficacy of the antioxidants is also determined by their biokinetics.
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PMID:Antioxidant functions of vitamins. Vitamins E and C, beta-carotene, and other carotenoids. 144 60

Water-soluble crystallins were obtained from clear human lenses of different age (4-81-year-olds) and lenses of individuals showing senile or diabetic cataracts. Levels of early glycation products were high in the high molecular weight material (HM) and the alpha-crystallin fractions, compared with beta- and gamma-crystallins. This difference becomes more prominent upon aging. The content of total early glycation products in HM and alpha-crystallin increases clearly with age, whereas levels remain relatively constant in the beta- and gamma-crystallins. There is an elevation of early products in cataractous lenses from diabetic individuals compared with those suffering from senile cataract. Specific non-tryptophan fluorescence (excitation/emission wavelengths 370/440 nm), used as an indicator for late glycation products, increased dramatically with age and was 2-fold higher in the diabetic subjects. Levels of fluorescence decreased in the order HM > alpha- > beta- > gamma-crystallins. The results suggest an increase in glycation rate in alpha-crystallin as a result of aging and diabetes, while the rate of glycation of beta- and gamma-crystallins remains almost constant.
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PMID:Glycation of crystallins in lenses from aging and diabetic individuals. 145 95

Lens opacification of the Ihara hereditary cataract rat (ICR/1 rat) was followed up with slit lamp biomicroscopy and photography up to 1 year after birth. The development of lens opacities was first recognized in the anterior superficial cortex of the equatorial region between 30 and 44 days of age. It progressed to maturity around 93-107 days after birth. Cataract development was classified into six stages. The increase of lens weight indicated a continuous lens growth after birth which seemingly even continued after the occurrence of lens opacities. After around 60 days of age, the lens showed a continuous increase of water content, suggesting a participation of increased water content in lens opacification.
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PMID:Age-related cataract in the hereditary cataract rat (ICR/1): development and classification. 147 73


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