The Optical Properties of the Anterior Segment of the Eye: Implications for Cortical Cataract

Dillon, James; Zheng, Lei; Merriam, John C.; Gaillard, Elizabeth R.

doi:10.1006/exer.1999.0687

Cited by 91 publications

(68 citation statements)

References 16 publications

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“…For example, the loss of a single positive charge in ␣A-crystalline due to a mutation of arginine to cysteine results in significant change of the tertiary structure of this protein (27), significant diminishment of its chaperon-like activity, and has been suggested as a probable cause for development of congenital cataract (28). By taking into account that UVA can penetrate in the human lens (29) and that the latter contains high concentrations of ascorbate (30), we can expect that OP-lysine could play an important role in photochemical processes in the lens, based on the data for its photo-bleaching shown in Fig. 12.…”

Section: Discussionmentioning

confidence: 99%

2-Ammonio-6-(3-oxidopyridinium-1-yl)hexanoate (OP-lysine) Is a Newly Identified Advanced Glycation End Product in Cataractous and Aged Human Lenses

Argirov

Lin

Ortwerth

2004

Journal of Biological Chemistry

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Post-translational modifications of proteins take place during the aging of human lens. The present study describes a newly isolated glycation product of lysine, which was found in the human lens. Cataractous and aged human lenses were hydrolyzed and fractionated using reverse-phase and ion-exchange high performance liquid chromatography (HPLC). One of the nonproteinogenic amino acid components of the hydrolysates was identified as a 3-hydroxypyridinium derivative of lysine, 2-ammonio-6-(3-oxidopyridinium-1-yl)hexanoate (OP-lysine). The compound was synthesized independently from 3-hydroxypyridine and methyl 2-[(tert-butoxycarbonyl)amino]-6-iodohexanoate. The spectral and chromatographic properties of the synthetic OP-lysine and the substance isolated from hydrolyzed lenses were identical. HPLC analysis showed that the amounts of OP-lysine were higher in water-insoluble compared with water-soluble proteins and was higher in a pool of cataractous lenses compared with normal aged lenses, reaching 500 pmol/mg protein. The model incubations showed that an anaerobic reaction mixture of N ␣ -tertbutoxycarbonyllysine, glycolaldehyde, and glyceraldehyde could produce the N ␣ -t-butoxycarbonyl derivative of OP-lysine. The irradiation of OP-lysine with UVA under anaerobic conditions in the presence of ascorbate led to a photochemical bleaching of this compound. Our results argue that OP-lysine is a newly identified glycation product of lysine in the lens. It is a marker of aging and pathology of the lens, and its formation could be considered as a potential cataract risk-factor based on its concentration and its photochemical properties.Glycation is a natural process observed in living systems, consisting in post-translational modifications of the side chains of amino acids in proteins by reactive carbonyl components. Glycation is a multistage and multidirection process. Initially, so-called "early glycation products" are formed. At this stage the modifications of amino acids are reversible. Further reactions lead to the formation of advanced glycation end products (AGEs), 1 which are relatively stable and tend to accumulate in biological or model systems with time. AGEs are important from a medical point of view because their concentration increases during aging (1) or in different medical complications such as cataract formation (2), retinopathy (3), and nephropathy (4).A natural protective mechanism against glycation and other harmful post-translational modifications is protein turnover. The vast majority of protein molecules has a limited life span and is periodically degraded and rebuilt. A remarkable exception are the proteins in lens fiber cells, especially those in the lens nucleus, being as old as the individual to whom they belong. Thus, the lens is a very appropriate tissue to study the accumulation of AGEs in vivo.The characterization and quantification of AGEs are based on chemical, spectral, and immunological techniques. Two major types of experiments are used for this purpose: either the properties of the b...

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Section: Discussionmentioning

confidence: 99%

2-Ammonio-6-(3-oxidopyridinium-1-yl)hexanoate (OP-lysine) Is a Newly Identified Advanced Glycation End Product in Cataractous and Aged Human Lenses

Argirov

Lin

Ortwerth

2004

Journal of Biological Chemistry

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“…The corneal transmittance at 300 nm is 32% in the rat [15] . The aqueous transmittance for monkeys has been published to be 90% [16] .…”

Section: Discussionmentioning

confidence: 99%

The Effect of Exposure Time on Maximum Acceptable Dose for Avoidance of Ultraviolet Radiation-Induced Cataract

Dong¹,

Söderberg²,

Ayala³

et al. 2005

Ophthalmic Res

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The effect of exposure time on maximum acceptable dose (MAD) for avoidance of ultraviolet radiation B (UVRB)-induced cataract was investigated. Sprague-Dawley rats were divided into 5 exposure time groups: 7.5, 15, 30, 60, and 120 min. Each exposure time group was divided into 5 dose subgroups: 0, 1, 2, 4, and 8 kJ/m². The rats were unilaterally exposed to UVR around 300 nm. One week after the exposure, macroscopic structure was recorded and lens forward light scattering was measured. MAD for avoidance of UVRB-induced cataract was estimated based on the dose-response function. MAD for avoidance of UVRB-induced cataract for 7.5, 15, 30, 60, and 120 min exposures was estimated to be 2.0, 1.4, 1.9, 1.8 and 2.2 kJ/m², respectively. In the exposure time domain 7.5–120 min, MAD for avoidance of UVRB-induced cataract depends on exposure time.

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“…A previous study on Chesapeake Bay watermen has determined a link between high UVB exposures and increased risk of cortical cataract 5 . Additionally, previous research has concluded that the UVA wavelengths (320 -400 nm) and perhaps visible radiation may also be implicated in the etiology of cortical cataracts in humans 6,7,8 . The UVA induced changes in the lens are affected by compounds that accumulate in the human eye.…”

Section: Introductionmentioning

confidence: 99%

Variations in the short wavelength cut-off of the solar UV spectra

Parisi

Turner

2006

Photochem Photobiol Sci

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The Optical Properties of the Anterior Segment of the Eye: Implications for Cortical Cataract

Cited by 91 publications

References 16 publications

2-Ammonio-6-(3-oxidopyridinium-1-yl)hexanoate (OP-lysine) Is a Newly Identified Advanced Glycation End Product in Cataractous and Aged Human Lenses

2-Ammonio-6-(3-oxidopyridinium-1-yl)hexanoate (OP-lysine) Is a Newly Identified Advanced Glycation End Product in Cataractous and Aged Human Lenses

The Effect of Exposure Time on Maximum Acceptable Dose for Avoidance of Ultraviolet Radiation-Induced Cataract

Variations in the short wavelength cut-off of the solar UV spectra

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