Thomas R. Shearer

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Selenite overdose cataract, an experimental model of nuclear cataract produced in young rats is reviewed. Topics include procedures for cataract production and assessment, metabolic and molecular changes in the epithelium of the lens, calcium accumulation, activation of calcium-activated protease system, mechanisms for crystallin precipitation,(More)
The purpose of this study was to identify the major protein components in adult human lenses and to analyse the specific age-related changes in these proteins using two-dimensional electrophoresis, Edman sequencing, and in conjunction with the data in the accompanying manuscript, mass spectrometry. The majority of changes in the two-dimensional(More)
A combination of Edman sequence analysis and mass spectrometry identified the major proteins of the young human lens as alphaA, alphaB, betaA1, betaA3, betaA4, betaB1, betaB2, betaB3, gammaS, gammaC, and gammaD-crystallins and mapped their positions on two-dimensional electrophoretic gels. The primary structures of human betaA1, betaA3, betaA4, and(More)
The purpose of this experiment was to measure the amounts of nickel and chromium released from a simulated orthodontic appliance incubated in 0.05 percent sodium chloride solution. The average release of metals was 40 micrograms nickel and 36 micrograms chromium per day for a full-mouth appliance. This was well below the average dietary intake of nickel and(More)
PURPOSE To determine the sequence of four rat beta-crystallins, confirm the sequences by mass spectrometry, and produce a two-dimensional electrophoresis (2-DE) map of soluble crystallins in young rat lens. METHODS New or additional sequences were determined for betaB1, betaB3, betaA3, and betaA4-crystallin cDNAs from Sprague-Dawley rats, and the deduced(More)
The mechanism causing loss of integrity of lens epithelial cells induced by an overdose of sodium selenite remains to be elucidated. The aim of the present experiment was to search for changes in gene expression in epithelial cells of lenses from rats developing selenite cataract. One day after injection of selenite into 12 day old rats, gene expression in(More)
Calpains are calcium-dependent intracellular nonlysosomal proteases that are believed to hydrolyze specific substrates important in calcium-regulated signaling pathways. Recently, an atypical member of the calpain family, calpain 10, was described, and genetic variation in this gene was associated with an increased risk of type II diabetes mellitus in(More)
The purposes of this experiment were to: (1), characterize the peptide aldehyde SJA6017, N-(4-fluorophenylsulfonyl)-L-valyl-L-leucinal, a newly synthesized inhibitor of calpain, and (2) test the effect of SJA6017 in preventing calcium ionophore-induced cataract in cultured rat lenses. In vitro, SJA6017 strongly inhibited purified m-calpain from porcine(More)
Abnormal activation of the protease calpain in the lens may be a cause of cataracts. Cataracts were induced in 10-day-old rats by a single overdose of sodium selenite. The water-insoluble protein from the opaque lens nucleus was separated by two-dimensional electrophoresis, electroblotted onto membranes, and the NH2-terminal sequence of partially degraded(More)
Molecular chaperone activity of lens alpha-crystallins is reduced by loss of the C terminus. The purpose of this experiment was to 1) determine the cleavage sites produced in vitro by ubiquitous m-calpain and lens-specific Lp82 on alpha-crystallins, 2) identify alpha-crystallin cleavage sites produced in vivo during maturation and cataract formation in rat(More)